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Investigating solutions for Cape Town to ensure water security

until 2040.

Prepared by Sekonyela Tieho (SKNTIE001)

for

Professor Neil Armitage

Submission date: 23 November 2015

i

Plagiarism Declaration

i) I know that plagiarism is wrong. Plagiarism is to use another’s work and to pretend that it

is one’s own.

ii) I have used the Harvard Convention for citation and referencing. Each significant

contribution to and quotation in this report form the work or works of other people has

been attributed and has been cited and referenced.

iii) This report is my own work

iv) I have not allowed and will not allow anyone to copy my work with the intension of passing

it as his or her own work.

Names Student number Signature

Sekonyela Tieho SKNTIE001

ii

ACKNOWLEDGEMENTS

I would like to express my thanks the follow the following people, without them the completion

of this research projection would not have been possible. My sincerest gratitude to Professor Neil

Armitage, for his supervision, assistance and guidance throughout the whole project. To Dr

Kirsty Carden, for guidance and providing me with contacts of my interviewees. To Lloyd

Fisher-Jeffers, for helping me to refine my draft and for giving his time when I needed the

consultations. To Nina Viljoen and Colin Mabudiro from the City of Cape Town for agreeing to

have interviews with me. To Barry Wood who directed me to Nina Viljoen. Finally, to Dr Kevin

Winter who gave me his time to interview him.

iii

Abstract

The City of Cape Town is expecting to experience a shortage of water by 2021. This is due to a

rapid increase in potable water demand as a result of, amongst others, population growth and

rising standard of living. In addition, Cape Town’s annual yield from current water sources is

expected to decrease due to the impact of climate change. Therefore, the City of Cape Town

needs effective solutions to increase the current water supply and/or decrease the demand of

potable water in order to prevent water shortage.

The aim of this research was to investigate potential solutions that can be implemented by the

City of Cape Town to prevent water deficits between 2015 and 2040. This was done by

identifying interventions which have not yet been implemented to their full potential in Cape

Town and quantifying the amount of water that can be saved or added to the system by further

implementing those interventions.

In this research, the adoption of water efficient devices (WED) in domestic sector and reduction

of water losses were identified as the two interventions that have the most potential in reducing

total demand of potable water in Cape Town. According to still et al. (2008), only 10% of the

South African population is using water efficient devices, therefore, there is a high potential of

saving a considerable amount of water through the use of these devices in Cape Town. The

calculations of this research showed that about 20% of the total water demand could be saved

annually if water WED could by adopted throughout Cape Town. The combined effects of water

efficient and water loss reduction has a potential of reducing water demand by 22.8%. The

implementation of these interventions will therefore postpone the occurrence of the predicted

water shortage by 6 years from 2021 to 2027.

The adoption of water efficient devices in domestic sector and reduction of water losses in Cape

Town could not meet the goal of this research which was to ensure water security until 2040.

Further interventions to decrease water demand could have been introduced, but climate change

is causing a decrease in water quantity from current sources. Therefore, additional water sources

that will increase the current water supply were investigated. After analysing all the potential the

additional water sources which were reviewed in this research, seawater desalination, re-use of

treated effluent and addition of more aquifers into the current system were considered to be the

best solutions. These additional water sources will increase the current water supply by a total of

259Mm3/annum to 658Mm3/annum which will postponed water shortage due to unrestricted high

water requirement growth by 15 years from 2021 to 2036.

Although Cape Town is considered as a water-stress region, the results of this research showed

that there are still potential interventions that can be implemented by the City of Cape Town to

prevent a water shortage until the year 2040. Furthermore, the projected water balance of Cape

Town for the year 2040 showed that, the demand will be 81Mm3 lower than supply if the City of

Cape Town can implement the suggested solutions in this research report. Therefore, the

suggested solutions will ensure water security beyond the year 2040. In addition, the 2040 water

iv

balance for Cape Town shows an improved water system which is more diversified as seawater,

treated effluent, groundwater and surface water are used at one time. This will therefore shift a

big dependence of water from surface water as it forms 98.5% of the City of Cape Town’s water

supply. As result, surface water will not be exhausted quickly.

Finally, this research project has successfully achieved its goal of searching for potential

solutions to ensure water security in Cape Town until 2040. In addition, the results of this

research can be improved or used as the basis for similar research in the future.

v

Table of content

Abstract iii

Table of contents v

List of Figures vii

List of Tables viii

1. Introduction 1-1

1.1 Background 1-1

1.2 Problem Statement 1-1

1.3 Objectives of the project 1-2

1.4 Research method 1-2

1.5 Scope and limitations 1-3

1.6 Plan of development 1-3

2. Literature review 2-1

2.1 Water scarcity in South Africa 2-1

2.1.1 Sustainable urban water management 2-2

2.2 Historical water demand in Cape Town 2-3

2.3 Current situation of water 2-4

2.3.1 Infrastructure leakage index 2-4

2.3.2 Water Wastage 2-5

2.3.3 Inefficient water use 2-7

2.3.4 Water end use 2-9

2.4 Water supply in Cape Town 2-10

2.5 Water demand in Cape Town 2-11

2.6 Future water requirements for the Cape Town 2-13

2.7 General recommended solutions to water deficit 2-15

2.8 User education and campaign initiatives 2-16

2.9 Leak detection and repair 2-17

2.10 Replacement of pipes 2-18

2.11 Pressure management 2-19

2.12 Water efficient devices 2-23

2.13 Tariff increase 2-24

2.14 Greywater harvest 2-25

2.15 Rainwater harvesting 2-25

2.16 Private boreholes/ wellpoints 2-26

2.17 Groundwater 2-26

vi

2.18 Desalination 2-28

2.19 Treated effluent 2-28

2.20 Surface water development 2-30

3. Procedure for wed calculations 3-1

4. Results and discussion 4-1

4.1 The situation of the city of Cape Town’s water supply 4-2

4.2 User education and campaign programs 4-4

4.3 Results of water demand reduction 4-5

4.4 Options for additional water supply 4-8

4.5 Treat effluent 4-10

4.6 Seawater desalination 4-10

4.7 Groundwater 4-11

4.8 Future projections of water demand 4-12

4.9 Final results 4-13

5. Conclusions and recommendations 5-1

References

Appendices

vii

List of Figures

Figure 2-1: South African gap of water demand and supply 2-2

Figure 1.2: Historical water demand of Cape Town 2-4

Figure 1-3: Historical trend of Cape Town’s infrastructure leakage index 2-5

Figure 1-4: International average water use per capita per day 2-7

Figure 1-5: Historical average consumption per capita per day in Cape Town 2-8

Figure 1-6: Household water use per end-use 2-10

Figure 1-7: Cape Town's sources of fresh water 2-11

Figure 1-8: Cape Town's sectoral water demand 2-12

Figure 1-9: Cape Town's water use cycle 2-13

Figure 1-10: Projected impacts of climate change on the available water supply 2-14

Figure 1.1: Projections for potable water demand 2-15

Figure 2-12: Example of the ways in which the City of Cape Town promotes awareness 2-17

Figure 2-13: Damage caused by a pipe burst 2-18

Figure 2-14: Existing and proposed sites for pressure 2-22

Figure 2-15: Historical tariff block for the City of Cape Town 2-24

Figure 2-16: Illustration of the geology for Table Mountain Group aquifer 2-27

Figure 2-17: Pipeline for distribution of treated effluent 2-29

Figure 1.2: Structure for chapter four 4-1

Figure 1.3: current water balance for Cape Town 4-2

Figure 1.4: Projections of Cape Town's water demand 4-3

Figure 1.5: Projections for high water requirements after water demand reduction 4-5

Figure 1.6: Projections for low water requirements after reducing water demand 4-7

Figure 4.6: Potential contribution by each additional water source 4-11

Figure 1.7: Projections of water demand after including additional sources

Figure 1.8: Final projections for high water requirements

4-12

Figure 1.9: Final projections for low water requirements 4-14

Figure 1.10: Cape Town's 2040 water balance 4-16

viii

List of Tables

Table 1.1: Performance classification of NRW 2-6

Table 1-2: Historical average water use per capita per day in Cape Town 2-8

Table 2-3: Advantages and disadvantages of pressure management forms 2-20

Table 2-4: Pressure management savings from the previous projects 2-21

Table 2-5: Survey results on the use of WED in South Africa 2-23

Table 2-6: Potential amount of treated effluent per year 2-30

Table 1-1: volumes and frequencies for domestic end-uses 3-1

Table 1-2: Water volume used per event by end-uses 3-2

Table 1-3: Reduction coefficients for low income households in Cape Town 3-2

Table 1-4: Average reduction coefficients for high and medium saving devices 3-3

Table 1.2: Multi-criteria analysis table 4-9

Table 1.3: Ranking of the alternatives' positive impacts 4-10

ix

Abbreviations

CoCT City of Cape Town

RWH Rainwater Harvesting

DWA Department of Water Affairs

FAVAD Fixed and Variable Area Discharge

GWH Greywater Harvesting

NRW Non-Revenue Water

PM Pressure Management

TE Treated Effluent: potable water replacement through re-use

WC/WDM Water Conservation / Water Demand Management

WED Water Efficient Device

PRV Pressure Reducing Valve

1-1

Tieho Sekonyela: Investigate solutions for Cape Town to ensure water security until 2040

Chapter 1: Introduction

1. Introduction

1.1 Background

Water resources are nowadays threatened by a rapid population growth, economic growth and

the rise in the standard of living. This is further exacerbated by a poor management of water and

inefficient water use (DWA, 2013a). Since the last century, the population of the world has

tripled, with the use of non-renewable energy being increased by a factor of 30 and the industrial

production being increased by a factor of 50 (Fariborz, 2012). As a result, water demand has

increased and resources with suitable quality are depleting due to urban, agricultural and

industrial uses (ibid.).

Climate change is one of the serious threats to water resources. It is caused by the emissions

of greenhouse gases, and predicted to continue changing even if the greenhouse gas emissions

are curtailed in accordance to Kyoto protocol (IPCC 2001; Mukeibir& Ziervogel, 2006). The

impacts of climate change are associated with extreme weather events such as floods, droughts

and heatwaves. In Cape Town, the impact of climate change is expected to be more evident by

2030, with an average atmospheric temperature increase ranging between 1.5°C and 2°C (ibid.).

This will cause a reduction in water yield from current water sources due to high evaporation

rate. As a result, Cape Town is expected to experience a shortage of water in 2020 if the increase

in water demand follows high water requirements’ trend and climate change impacts occur

(DWAF, 2013b). However, this water shortage will happen if the City of Cape Town cannot find

alternative sources of water and if water demand growth remains unrestrained.

There has been a considerable amount of work done to ensure water security for the City

of Cape Town. Historically, it has been easy to meet the increasing water demand largely through

the construction of new dams (DWA, 2013a). However, large augmentation schemes like dams

are expensive to construct and lengthy. Furthermore, most of the economical viable sites to

construct more dams are now developed and in use (DWA, 2013a). As a result, the focus has

recently shifted to the demand management and efficient use of water (National Planning

Commission, 2012). In 2001, the City of Cape Town developed Water Conservation and Water

Demand Management (WC/WDM) policies and strategies to reconcile its limited water supply

with the increasing demand (Melissa, 2015). In the period between 2011 and 2013, WC/WDM

initiatives reduced water demand by 4.8% and the demand of water was expected to increase due

to population growth (DWA, 2013b). This showed the potential of WC/WDM initiatives in

decreasing water demand.

1.2 Problem Statement

Climate change can be thought as a way of shifting climate variables such as temperature and

precipitation from their average states (Mukeibir& Ziervogel, 2006). Climate models predict an

increase in average atmospheric temperature and a decrease in the frequency of annual

1-2



precipitation with the intense rainfall when it happens (Altman & Spencer, 2010). As Cape

Town’s climate is expected to change, this will reduce the annual yield of dams due to high

evaporation rates as a result of the increasing atmospheric temperatures. The demand of water,

on the other hand, is continuing to increase due to population growth and the rising standard of

living. These factors are therefore exhausting the available water in the current sources.

The City of Cape Town currently depends mainly on surface water and most of the viable

sites to construct more dams have already been developed. Therefore, alternative sources of

additional water supply need to be found. Alternatively, effective water demand management

strategies can be developed and implemented in order to reduce water demand.

1.3 Objectives of the project

The main goal of this research project was to investigate solutions for the City of Cape Town in

order to ensure water security until 2040. To achieve this, the following was done:

The extent of the Cape Town’s water crisis was investigated.

Potential solutions to combat Cape Town’s water crisis were investigated, and the best

solutions were selected.

The projections of Cape Town’s water supply between 2015 and 2040 were carried out to

check the effectiveness of the suggested solutions.

Finally, Cape Town’s water balance for 2040 was developed to show how Cape Town’s

water situation will look like in 2040.

1.4 Research method

This section outlines the method used to achieve the goal of this research. The following

procedure was followed to carry out this project research:

Firstly, a literature review was done to gain a better understanding of the extent of water

crisis facing the City of Cape Town. In addition, future plans and the abilities of the City

of Cape Town to combat this crisis were investigated through the literature. This was to

avoid proposing the solutions that the City of Cape Town will not be able to implement or

those that cannot be applicable to Cape Town. Moreover, the literature was studied to learn

various methods of how to calculate water use reduction through the adoption of water

efficient devices, since this is proposed as one of the best alternatives to save water.

Several interviews with the professionals from the Department of Water and Sanitation in

the City of Cape Town were conducted. The reason for this was to acquire information

about the current water situation in Cape Town. This was to obtain the information that

was missing in the literature. Furthermore, the purpose of these interviews was to acquire

1-3



updated data to do calculations. In addition, some of the interviews or consultations were

done with the academics from the University of Cape Town.

With the data obtained from the City of Cape Town and literature, the amount of water use

that can be reduced through the installation of water saving devices was calculated.

Furthermore, this research used the already available data to carry out projections and

calculations since the experiments and site measures were out of the scope of this research.

The multi-criteria analysis approach formed big part of this research. Due to the large

amount of information obtained in this research, multi-criteria analysis was used as a tool

to make decision in choosing the best recommended solutions in this report.

Finally, Microsoft excel was used to carry out all the calculations and generate graphs for

interpretation and analysis of the results.

1.5 Scope and limitations

This research is limited to the region of Cape Town. Whilst the impacts of climate change are

expected to negatively affect the whole ecosystem in Cape Town, this research focused only on

the impacts of climate change on water resources. Furthermore, although climate change will

affect both quality and quantity of water resources in Cape Town, the research was focused only

on identifying the potential solutions to water shortage and not to the quality.

This research investigated the solutions to ensure water security until the year 2040.

Attention was not given to the time beyond 2040, although some of the suggested solutions will

have an effect on the water system after 2040.

The calculations for water savings through the adoption of water efficient devices were

limited to domestic sector. This is because potable water use in the domestic sector is about

47.6% of the total water demand, therefore there is a potential of realising high water saving by

reducing water use in this sector.

1.6 Plan of development

This introductory chapter introduces the topic and gives a motivation for the research. It also

explains briefly how the research was conducted. Chapter 2 provides a literature review on the

situation of water resources in Cape Town. It also reviews water supply crisis which is caused

by the increasing water demand in Cape Town and provide the general recommended solutions

to these situations. Chapter 3 explains the method used to calculate the amount of water that can

be saved through the adoption of water efficient devices. Chapter 4 presents the findings of the

research whilst the Chapter 5 gives conclusions and recommendations.

2-1


Chapter 2: Literature review

2. Literature review

In order to provide an effective solution to water crisis that is facing Cape Town, a literature

review was first carried out to gain a better understanding of the extent of the problem. This

chapter starts broadly by explaining the situation of water supply in South Africa. It continues

by narrowing down to Cape Town, whereby history, current situation and future projections of

potable water demand are discussed. Then, general recommended solutions to water crisis that is

facing Cape Town are provided.

2.1 Water scarcity in South Africa

South Africa has annual rainfall of approximately 450mm which is below the world’s average

annual rainfall of 860mm (DWAF, 2004). Most of the South African rain falls along the eastern

and southern coasts. The driest (western) part of the country receives annual rainfall which is

less than 200mm (ibid.). South Africa is therefore classified as a semi-arid country; currently

ranked 30th driest country in the world with less water available per capita when compared to

some of the water-stressed countries such as Namibia and Botswana (DWA, 2013a).

Whilst there is an expectation of water shortage in South Africa, this is not a unique

problem to this country. It is predicted that 3.5 billion people, which is about 50% of the world’s

population, will face water scarcity around the world by 2025 (Governing Board Induction

Manual, 2011). In South Africa, it is projected that water demand will exceed current potable

water supply by 2025 if the usage trend remains the same (ibid). Listed below are some of the

factors which are expected to place further pressure on water resources unless mitigation actions

are put in place:

Climate change: is expected to reduce the current annual water yield due to the increase

in average atmospheric temperature, which will in turn increase evaporation rate of surface

water. In addition, climate change is expected to decrease annual rainfall frequency.

Economic growth: is expected to cause an increase in current water demand.

Population growth: a number of people is related to the amount of water use, therefore

population growth will also rise the current water demand.

Standard of living: like economic and population growths, the rise in standard of living

causes the increase in water demand and it is considered as the main driver of water demand

growth.

There has been a great concern about the growing water shortage in South Africa (Turpie et al.,

2008). This is because the current policies of the Department of Water and Sanitation (DWS) are

not adequate to effectively address the expected water crisis that is faced by the country (Hidden

& Cillier, 2014). As a result, there is a gap between water demand and supply. This gap was

modelled by Hidden & Cillier (2008), and the results of the model are show in Figure 2-1.

2-2



Figure 2-1: South African gap of water demand and supply

(Heden & Cilliers, 2014)

2.1.1 Sustainable urban water management

Sustainable Urban Water Management (SUWM) is a term that is used to describe sustainable

water management in the wider sense (Brown et al., 2007). SUWM treats water cycle as an

integrated system that needs to be managed in a way that does not compromise the needs of both

people and the environment.

The current water management approaches are considered not sustainable in the long term

(Brown et al., 2007). As a result, there has been a growing interest in finding alternative water

management approaches (Brown et al., 2007). Furthermore, “most of these approaches adopt

very similar philosophical methods but vary in the scale or extent of their application” (Coulson,

2014). Some of the components of Sustainable Urban Water Management (SUWM) approach

are:

Water Sensitive Urban Design (WSUD)

Total Water Cycle Management (TWCM)

Integrated Urban Water Management (IUWM)

Sustainable Urban Design System (SUDS)

Water Conservation and Demand Management (WC and DM)

Integrate Water Resource Management (IWRM)

Low Impact Development (LID)

2-3



According to the City of Cape Town’s ‘Long term water conservation and demand management

intervention’ report (CoCT, 2007), all sustainable water management approaches have similar

objectives, which are as follows:

Reducing potable water demand,

Increasing the number of alternative sources of water,

Increasing infiltration to recharge groundwater and attenuate stormwater flows,

Reducing wastewater discharge and lowering stormwater flows to mitigate environmental

degradation of downstream waterways.

In general, these objectives are concerned with efficiency and sustainability of water use. The

conventional water management approach was water demand driven, which means a focus was

only to increase water supply through the construction of new dams. Currently, most of the

economically viable sites for dam constructions have now been developed. As a result, South

Africa needs to adopt a new water management approach to combat its water crisis.

2.2 Historical water demand in Cape Town

The historical water use of Cape Town is marked by three sharp declines which happened

between 1976 and 1997, and again between 1995 and 1996. The last sharp decline happened

between 1999 and 2000.

In 2000, water demand reached 499Mm3/annum, whilst winter rainfall simultaneously fell

below average. Shortfalls then were experienced and water restrictions were introduced to

prevent the exhaustion of available water in the sources. These water restrictions resulted in a

temporary decrease in water demand, which was then followed by a progressive return to a

relatively high water usage of 476Mm3/annum in 2004. In the same year (2004), a severe drought

was experienced and water restrictions were introduced again. In addition, further water

restrictions were introduced again in 2006, and that resulted in the water demand drop to

465Mm3/annum (DWA, 2007a).

Figure 2-2 shows the trend that was followed by potable water demand over the years

between 1996 and 2006. It can be seen that over the period between 2001 and 2005 potable water

demand did not return to the level it was before the implementation of water restrictions in 2001.

The yellow arrows show that the increasing rate of water demand is slower than prior to 2001. It

can then be concluded that water restrictions have a potential to change water users’ behaviour.

To clarify Figure 2-2, the water demand reduction in the graph was caused by the combined

effects of water tariff increase, user education and Water Demand Management (WDM)

initiatives (DWA, 2007a).

2-4



Figure 2.2: Historical water demand of Cape Town (DWA, 2007)

2.3 Current situation of water

The City of Cape Town receives the bulk of water from winter rainfall with annual average of

464mm (Tadross & Peter, 2012). It relies mainly on dam and reservoir water storages to supply

water throughout the year, and to meet high water demand during the dry summer months. The

City of Cape Town’s water sources consist of surface water and groundwater with proportions

being approximately 98.5% and 1.5% respectively (Water Service Development Plan, 2013).

2.3.1 Infrastructure leakage index

Infrastructure Leakage Index (ILI) is defined as Current Annual Real Losses (CARL) divide by

Unavoidable Annual Real Losses (UARL). Municipalities use infrastructure leakage index to

assess their management of real water losses and the performance of their water distribution

systems. A well-managed water reticulation system has a value of infrastructure leakage index

equal to one. However, it is uneconomical to achieve this value in many countries (WCWDM

Strategy, 2015). As a result, countries accept a value that is greater than one, and the

internationally acceptable ratios of ILI range between 2 and 10 (ibid.).

Figure 2-3 illustrates a trend of infrastructure leakage index and real water losses for Cape

Town’s water reticulation network. It can be seen that there has been a continuous decline in the

levels of annual real losses between 2010 and 2013, while the expected unavoidable real losses

2-5



remained almost the same throughout this period. It can be concluded that there have been

successive improvements in the water distribution network of Cape Town between 2010 and

2013.

The International Water Association (IWA) consider Infrastructure Leakage Index (ILI)

ratio which is below 2 as world class management (Delgado, 2008). The ILI ratio for the City of

Cape Town is equal to 1.88 and according to IWA, Cape Town’s water infrastructure is

performing well.

Figure 2-3: Historical trend of Cape Town’s infrastructure leakage index

(CoCT, 2015)

2.3.2 Water Wastage

The total water loss in Cape Town is currently estimated at 15.8% of the total potable water

demand, which is equal to 58.3Mm3/annum. This amount includes bulk losses, reticulation losses

and apparent losses excluding unbilled authorised water use. This amount has increased from

46.3Mm3/annum in 2013/2014 financial year, which means Cape Town’s infrastructure leakage

index has also increased over this short period. (CoCT, 2015)

2-6



According to WCWDM Strategy report (2015), the minimum night flows where there are no

industries are assumed to be water wastage as a result of:

Leaks in the reticulation systems,

Leaks within customers’ properties,

Indiscriminate water wastage,

And automatic flushing urinals.

It is believed that leakage will always be available as a form of Unavoidable Annual Real Loss

(UARL), but there is often an extra leakage that can be reduced (McKenzie, Siqalaba & Wegelin,

2012). In the case of Cape Town, currently the excess leakage is 0.8% of the total daily demand

and that amounts to 7.51Mm3/day. The Reconciliation Strategy report (2007) for the City of Cape

Town contains some of the initiatives which aim at eliminating extra leakage, which are as

follows:

User education and campaigns: with these initiatives, the City of Cape Town aims at

making the community aware of water crisis and teaching users how to save water. These

initiatives involves informative billing, media marketing, water user forums, outreach

programmes and so on.

Leakage detection and repair: the City of Cape Town believes that its unavoidable annual

real losses (UARL) cannot be reduced economically to below 15% of the total water

demand. The target is therefore the excess percentage of water loss above UARL. In

addition, this initiative of leakage detection and repair is targeting low income household

areas, because people in those areas cannot afford regular maintenance and repair.

(WCWDM Strategy, 2015).

Elimination of automatic flushing urinals: here the City of Cape Town is planning to

replace all the automatic flushing urinals in public places with user-activated flushing

urinals and waterless urinals.

Table 2.1: Performance classification of NRW (McKenzie, 2012)

Non-Revenue Water (NRW) is defined as the amount of water supplied into the system

that does not generate revenue. The City of Cape Town’s NRW is currently 22.3%, and this is

Classifications Description

< 15 % Low level of NRW, very good performance

15 - 30 % Low level of NRW, good performance

30 – 40 % Average level of NRW, average performance

40 – 50 % High level of NRW, poor performance

>50 % Very high level of NRW, very poor performance

2-7



considerably better compare to average NRW of South Africa which is 36.8% (CoCT, 2015;

McKenzie et al.,2012). The City of Cape Town’s NRW is classified as good performance

according to Table 2-1. Moreover, the City of Cape Town is hoping to improve and reduce its

non-revenue water to 19% (ibid.).

2.3.3 Inefficient water use

In addition to water wastage, a significant amount of water is lost through inefficient water use

(WCWDM, 2015). This is a volume of potable water that can be saved by installing Water

Efficient Devices (WED) and/or through changing the users’ behaviour. WEDs are devices that

use less water to perform the same function as the standard devices without altering the primary

objective. For example, when a toilet is flushed, the objective is to clean the pan and facilitate

the transportation of material to wastewater treatment works, and water efficient devices carry

out this objective with less volume of water.

It has been mentioned that South Africa is a semi-arid country. However, it has average

water use of 235Ɩ/capita/day for domestic use, which is above the world’s average of

173Ɩ/capita/day (Siqalaba et al.,2012). Figure 2-4 shows a comparison of countries’ average

water use per capita per day. The horizontal red line represents world’s average and the yellow

bar is the average water use per capita per day in South Africa. It can be seen that most of the

countries fall below world’s average with the few including South Africa being above world’s

average water use. It can then be concluded that South Africa is using water inefficiently.

Figure 2-4: International average water use per capita per day (Siqalaba et al., 2012)

2-8



In Cape Town, water use per capita per day is calculated using equation 2.1.

Water use (litres per capita per day) = (𝐵𝐴𝐶−𝐼𝑛𝑑𝑢𝑠𝑡𝑟𝑖𝑎𝑙 𝑤𝑎𝑡𝑒𝑟 𝑢𝑠𝑒)+𝐴𝑈𝐶

𝑇𝑜𝑡𝑎𝑙 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 (2.1)

Where:

BAC : Billed authorized water use

UAC : Unbilled authorized water use

Table 2-2 presents the historical average water use per capita per day in Cape Town. It shows

that water use has decreased continuously during the period between the years 2010 and 2014,

and this can be seen clearly in Figure 2-5. The last recorded water use was in 2014, and it was

180Ɩ/capita/day which is below the country’s average of 235Ɩ/capita/day but more than

international average by 7Ɩ. From this information it can be concluded that there is amount of

inefficient water use that can be saved from Cape Town.

Table 2-2: Historical average water use per capita per day in Cape Town (CoCT, 2012)

Sub sector % 2009 2010 2011 2012 2013 2014

Indoor use 75 161 163 162 155 149 135

Outdoor use 18 39 39 39 37 36 32

Leaks 7 15 15 15 14 14 13

Total 100 215 218 217 207 198 180

Figure 2-5: Historical average consumption per capita per day in Cape Town

(CoCT, 2012)

2-9



The users’ behaviour has a big impact on the way water is used in urban areas (Hassell & Carry,

2007; Willis et al., 2007). The behaviour of water users can be changed by providing awareness,

understanding and appreciation of water and the environment in which they live (Willis et al.,

2007). The initiatives such as user education and water awareness campaigns can help to change

users’ behaviour. The results of the water use survey which was conducted before the

development of the Reconciliation Strategy Study (2008) indicated that 20% of the community

changed their behaviour due to user education programs (DWA, 2009). Therefore, there is a

potential of reducing inefficient water use through user education and campaign initiatives.

2.3.4 Water end use

The amount of water that is used inefficiently for garden watering accounts for up to 40% of total

demand (Jacobs et al.,2007). Since the amount of water use for garden watering varies all the

time due to weather conditions such as rainfall, a conservative value of 20% is often used for

inefficient water use (ibid.). According to Water Conservation and Water Demand Management

(WCWDM) Strategy (2015), the efficiency of water use for garden watering can be improved

significantly through Schedule 1 of Water Bylaw for the City of Cape Town, which is as follows:

Irrigation scheduling states that no watering should take place between 10h00 and 16h00,

Mulching should be encouraged,

Plantation of indigenous plants should be encouraged,

The use of grey water should be promoted to reduce the dependence on potable water for

irrigation of plants,

Replace grassed areas with alternative ground covers,

And use pool covers to reduce evaporation.

The City of Cape Town is currently in the process of conducting a household survey across all

income households in order to have a better understanding of how water is used within the

households (WCWDM, 2015). This will assist in finding an effective solution to water crisis that

is facing Cape Town.

The water end-uses that contribute the most in water demand turn to contribute more in

water saving if they are being managed efficiently (Jacobs et al., 2007). Figure 2-6 shows a

general breakdown of water use by household’s end-uses. It can be seen that personal cleansing

uses more water than other categories. Therefore, it can be concluded that there is a potential to

realise a greater water saving from this category if it can be managed efficiently.

2-10



Figure 2-6: Household water use per end-use (Jacobs et al., 2007)

2.4 Water supply in Cape Town

Western Cape Water Supply System (WCWSS) currently allocates 399Mm3/annum of water to

Cape Town at 90% level of assurance. The water is transported through a bulk conveyance pipe

network which is 630km, and it serves over 1.1 million households with a population of over 3.8

million. (CoCT, 2015)

According to the Water Services Departmental Sector Plan (2015), one of the City of Cape

Town’s goal is to make the provision of water services affordable to poor households. As a result,

free basic water of 6kƖ is supplied to all residents every month. In addition, the first 4.2kƖ of

sewerage is transported to the wastewater treatment works and treated free of charge for all users.

The registered indigent households are provided with a free basic water of 10.5kƖ per month, and

in Cape Town a total number of 288 724 households qualifies for this free basic water (WSDP,

2015).

Figure 2-7 shows the sources of Cape Town’s raw water and how much each source is

contributing to Western Cape Water Supply System (WCWSS). It can be seen that most of the

raw water comes from the Department of Water Affairs’ water schemes which provides about

73% of the total supply. The City of Cape Town obtains the remaining 27% from its water

sources.

2-11



Figure 2-7: Cape Town's sources of fresh water (CoCT, 2015)

2.5 Water demand in Cape Town

Currently Annual Average Daily Demand (AADD) for the City of Cape Town (CoCT) is

952.5MƖ (CoCT, 2015). Domestic sector’s demand for potable water is 46.7 % of the City of

Cape Town’s total water demand (ibid.). It can be seen in Figure 2-8 that domestic sector’s

demand for potable water far outweighs that of the other sectors. Furthermore, domestic water

use has decreased from 48.7 % in 2013/2015 financial year. As mentioned earlier, a decrease in

domestic water use has a potential to realize a considerable water saving for the City of Cape

Town. However, the total water demand has increased from 862MƖ to 952.5MƖ per day between

2014 and 2015, although domestic water use decreased (WCWDM Strategy, 2015; CoCT, 2015).

2-12



Therefore, a decrease in domestic water use alone is not effective, as a result, the demands for

other sectors need to be reduced.

Figure 2-8: Cape Town's sectoral water demand (CoCT, 2015)

Water Conservation and Water Demand Management (WC/WDM) initiatives have been

introduced to reduce the rapid increasing water demand in the City of Cape Town (CoCT). This

shows that the City of Cape Town has moved from the conventional approach that was focusing

on reconciling water demand by increasing the water supply alone to sustainable water demand

management approach.

During the period between 2011 and 2013, a big success of Water Conservation and Water

Demand Management (WC/WDM) initiatives was realised. During that time the total water

demand decreased by 4.8% when it was expected to increase because of the population growth

of 2.9% per annum as result of childbirth and immigration (Ross, 2014). Water Conservation and

Water Demand Management initiatives have a potential to reduce water demand significantly,

but the City of Cape Town has not yet implemented these initiatives to their full potentials.

To date the following initiatives of the Water Conservation and Water Demand

Management (WC/WDM) initiatives have been implemented. In addition, these initiatives have

resulted in a considerable savings based on the results of the previous projects. The amount of

the savings of these initiatives are provided in Water Conservation and Water Demand

Management Strategy report (2015).

8.1%

2.5%

47.1%

10.1%

11.0%

14.8%

6.5%

Commercial

Industrial

Domestic

Other

Water supplied to external

Water losses

Unbilled Authorised

Consumption

2-13



Pressure management

Treated effluent

Retrofit and leak repair

Pipe replacement

Leak detection and

Meter replacement

Repair on connections

Figure 2-9 is an overview of the water use cycle within the City of Cape Town. The figure intends

to graphically summarize this section on current water situation of Cape Town by showing how

water is distributed. The estimations of water demand and water losses are provided in water

balance diagram in Chapter 4.

Figure 2-9: Cape Town's water use cycle (CoCT, 2015)

2.6 Future water requirements for the Cape Town

The average atmospheric temperature is expected to rise by 1.5°C to 2°C by 2050. This will

increase a rate of evaporation in open bodies of water, as a result, stored water will be lost through

high evaporation rate (Mukeibir & Ziervogel, 2006). Precipitation is expected to decrease in

2-14



frequency but increase in intensity when it happens (ibid.). An increase in evaporation rate and

a drop in annual rainfall frequency will therefore reduce the City of Cape Town’s annual yield

for current water sources.

Figure 2-10 illustrates the projected impact of climate change on the City of Cape Town’s

water quantity. The water yield of Cape Town from current sources is expected to decrease

linearly. According to these projections, climate change will cause the City of Cape Town to lose

approximately 20Mm3 by 2040. Therefore, water yield for the City of Cape Town is expected to

drop to 379Mm3 in the year 2040. In order to prevent water shortage before 2040, additional

water sources need to be found.

Figure 2-10: Projected impacts of climate change on the available water supply

(CoCT, 2015)

High Water Requirement (HWR) growth and Low Water Requirement (LWR) growth for

the City of Cape Town are estimated at 3.38% and 2% respectively. As water demand increases,

climate change on the other hand is causing the quantity of the current water yield to decrease

linearly as shown in Figure 2-10. As a result, climate change shortens the time that will take the

increasing water demand to reach the quantity of available water from current sources. Therefore,

climate change mitigation and adaptation measures need to be implemented.

300

320

340

360

380

400

420

2000 2005 2010 2015 2020 2025 2030 2035 2040 2045

Vo

lum

e (M

illi

on m

3)

Years

Water supply Climate impact

Yield drop by

2014

2-15



Figure 2-11 shows the potable water demand projections for the City of Cape Town (CoCT).

There would have been a water shortage in 2012 had water conservation and water demand

management initiatives not been implemented before that year (2012). Water conservation and

water demand management initiatives were further implemented to avoid projected water

shortage in 2016, and that postponed water shortage by 4 years. Water demand is now expected

to reach the current water yield by 2020 based on average water demand growth of 3.38% when

2013 is used as the baseline. As a result, new water augmentation schemes are needed by 2020

or water demand should be reduced in order to avoid the expected water deficit.

Figure 2-1: Projections for potable water demand (WCWDM, 2015)

2.7 General recommended solutions to water deficit

In this research, the solutions to prevent water deficit include reduction of potable water demand

and improvement of water use efficiency. In addition, different augmentation schemes to increase

and/or diversify water supply in order to have a range of supply options were also investigated.

According to Flack (1981), four basic approaches to improve water use efficiency are as follows:

2-16



Structural methods: are concerned with the improvement of the physical infrastructure

for efficient water distribution. Examples for this approach include the use of water saving

devices to reduce the amount of water use. Other example is the installation of pressure-

reducing valves to manage water pressure in the system and reduce leakages. The

performance of this approach can be assessed by calculating the infrastructural leakage

index.

Operational methods: include operational interventions that aim at improving the

efficiency of water distribution system. Leak detection and repair is a good example for

this approach. For this method to be effective, operation and maintenance need to be

proactive.

Economic methods: involve the increase of tariffs to change the behaviour of customers

towards water use.

Socio-political methods: here user education and campaigns, as well as water laws and

regulations are used to control the water usage.

2.8 User education and campaign initiatives

User education and campaigns are initiatives which aim at encouraging voluntary water

conservation, either by altering the behaviour of water users or by promoting the adoption of

Water Efficient Devices (WED). Media marketing, water use forums, outreach programmes,

school education programs and websites can be used to achieve the objectives of these initiatives.

Furthermore, these initiatives are considered as the most important aspects of Water Demand

Management (WDM) projects. According to McKenzie (2014), the well-designed projects often

do not succeed because community may have not been included into the design process.

Smith & Visser (2014) assessed the impact of spreading information about water saving

tips to water users. A sample of 280 000 low income households in Cape Town was used. Three

aspects of this assessment were as follows:

Increasing the understanding and awareness of households’ water use,

Giving tips on how to save water,

Providing water use comparisons to neighbours.

A reduction of about 1% of water use was achieved from simply reporting water saving tips

(ibid.). This percentage is equivalent to water demand of 3.3Ɩ/household/day. This shows that

user education and campaign initiatives have a potential to contribute to the reduction of water

use.

Altering human behaviour is a continuous process, therefore user education and campaigns

need to be invested in a long term and be kept interesting and relevant to the users (CoCT, 2007).

In this way, both users and suppliers will not give up along the way and the objectives of the

2-17



initiatives can be achieved. However, it is difficult to predict and measure the success of these

initiatives.

The informative billing is one of the tools that can be used to improve awareness and make

the process interesting. This involves providing consumers with information of their water use

for each month. Accompanied by this information, can be a trend of user water demand for a

certain period, and an average water use of the municipality for comparison. Together with this

information, tips on how to reduce water use can be included. By providing this information in a

format that can be easily understood by water users, will improve awareness about the importance

of saving water.

Figure 2-12 shows one of the ways in which the City of Cape Town (CoCT) is promoting

the awareness about the importance of saving water. The tips on how to save water are written

on the wall, but there is no information on how to report water wastage, or enquire information

about water usage. This shows that the City of Cape Town needs to improve the interaction with

the community.

Figure 2-12: Example of the ways in which the City of Cape Town promotes awareness

(CoCT, 2015)

2.9 Leak detection and repair

The reduction of water loss in a form of leakages can be achieved through structural and

operational approaches. Firstly, the cause of this leakages need to be understood to effectively

2-18



solve the problem of water loss. Listed below are some of the causes of leakages in Cape Town

according to Mabudiro (2015):

Aging of materials – corrosion and condition

Poor laying conditions

Poor operations – for example air in pipes

Pressure surge – faulty valves

Failing joints

Working pressure of pipes

The study conducted by Couveils (2013), where on-site leakages were investigated in Cape

Town, showed that 16.4% of 402 properties which were investigated had on-site leakages. Langa

was found to have the highest occurrence of leakages (42.3%) and Mowbray with the lowest

occurrence of leakages (3.8%). This difference in leakages is due to the income levels of the two

areas with Mowbray being a middle income area and Langa being a low income area. Since

Langa is a low income area, it can be assumed that residents are not able to afford regular

maintenance and repair of pipes, and this resulted in the high amount of leakages. Therefore,

domestic leak detection and repairs need to be implemented and focus mainly on low income

households as planned in the Reconciliation Strategy (2007).

A recent leak detection and repair programs which have been implemented were in

Highbury and Wesbank, and together they saved 76 MƖ/annum (Water Conservation and Water

Demand Management Strategy, 2015). The amount of water that can be saved through leak

detection and repair programs depends on the extent to which these programs are implemented.

As a result, many of these programs are required in order to increase the amount of water that

can be saved.

2.10 Replacement of pipes

Figure 2-13: Damage caused by a pipe burst (Mabudiro, 2015)

2-19



Poor maintenance of pipes and aging of material contribute to water losses. According to the

presentation by Mabudiro (2015), the City of Cape Town (CoCT) replaces pipes only when their

collateral damages are severe, and on average 324 kƖ of water is lost per pipe burst. This approach

that is used by the CoCT is costly and life threatening since poorly maintained mains can affect

the surrounding environment. Therefore, a proactive operation and maintenance (O&M) of water

infrastructure need to be implemented to reduce water losses. Figure 2-13 shows the damage that

was caused by a pipe burst.

2.11 Pressure management

There is a relationship between pressure and leakage rate. The amount of water lost through the

leaks increases with the increase in pressure (Van Zyl & Clayton, 2007). The Fixed and Variable

theory (FAVAD) is commonly used to explain the relationship between pressure and leakage

rate (ibid.). The theory is explained as follows: A Fixed area discharge is that of an orifice in iron

or steel pipe whereby the orifice’s size does not change with the increase in pressure, as a result,

a 100% increase in pressure will cause a 41% increase in leakage (McKenzie & Wegelin, 2010).

A Variable area discharge is that whereby an orifice changes with an increase in pressure. The

leakage increase by as much as 8 times the original value if orifice changes in size (ibid.).

Therefore, a pipe material plays an important role in controlling the amount of leakage.

During the periods of low water demand, mostly at night, the pressures in the water

reticulation systems increase and contribute to the amount of leakage rate. According to

McKenzie (2014), pressure management is one of the most important initiatives of Water

Demand Management (WDM) which helps to reduce water losses. It is able to reduce the

probabilities of new leaks’ development and pipe burst by 90% or more through the reduction of

unnecessarily excess pressures (Lambert& Fantozzi, 2010). As a result, pressure management

prolongs the lifespan of the reticulation systems and result in financial saving.

Pressure management schemes are not effective at all areas they are being implemented

(Meyer et al.,2009). Therefore, it is vital to take feasibility studies for each proposed pressure

management project (ibid.). In addition, pressure management schemes need to be implemented

as a part of a well-managed and well maintained reticulation systems in order to perform

effectively (McKenzie, 2014).

Listed below are aspects of an area that need to be taken into consideration before

implementing pressure management programs according to Meyer et al. (2009):

Elevation – Low lying areas are likely to experience high pressure, as a result, the pressure

management can be effective when applied to low lying areas.

High minimum night flows – Areas with high leakage will still have high water flow at

night, therefore, there is a potential of high water savings in these areas.

Size of an area – Large areas usually have long mains and more connections, this often

result in more leakage than small areas.

2-20



Strategic facilities – in areas where hospitals are present, pressure management should be

avoided or a special form of pressure management should be implemented, so their

pressure may be dependably constant.

Currently there are three forms of pressure management, each with a unique application and

advantages as well as disadvantages:

Fixed outlet – regulates maximum pressures entering the system using Pressure Reducing

Valve (PRV).

Time modulated – operates the same as fixed outlet but it enables pressure to be further

reduced during specified off-peak hours.

Flow modulated – here pressure can be controlled continuously since the live data is sent

back to pressure controller at the inlet.

Table 2-3: Advantages and disadvantages of pressure management forms

(McKenzie&Wegelin, 2010)

Form of pressure

control

Advantages

Disadvantages

Fixed outlet

Simple to install and only requires PRV.

The cheapest option to install

Simple maintenance and operation.

Pressure cannot be adjusted

at different times of the day,

and thus missing further

saving opportunity.

Time modulated

Pressure can be reduced at specific, pre-

defined times of the day.

Electronic equipment is simpler and cheaper

than that for flow modulated.

Electronic controller is simple to set up and

operate.

More expertise required to

operate and maintain than

fixed outlet.

Does not react to the demand

for water and thus fire-

fighting requirements can be

a problem during the reduced

pressure periods.

Flow modulated

Will provide the highest possible savings in

the system.

Can accommodate fire-fighting

requirements.

Installation is costly.

Operation requires

specialised technical skills.

More opportunity for

equipment to fail.

2-21



Table 2-3 summarises the advantages and disadvantages of each form of pressure management.

The aim of this table is to assist in the selection of a desired pressure management form by

comparing advantages and disadvantages of the types of pressure management.

To quantify the water savings through pressure management schemes, the following

information is required:

Length of mains

Number of residential and non-residential properties

Identification of large non-residential users

Number of connections

Condition of the network (age, reported bursts, etc.)

Population figures

Pressure exponent (N1)

Logging of Average Daily Demand (ADD) and Minimum Night Flow (MNF) flow rates

The information listed above is used as the input in FAVAD equation below.

𝐿1

𝐿0= (

𝑃1

𝑃0)

𝑁1

(3.1)

The logging results give current pressure (P0) which can be compared to the level of service

requirements to obtain excess pressure that can be reduced to new lower pressure (P1).The

pressure exponent (N1) determines the character of the system. L1 and L0 represent new leakage

flow rate and old leakage flow rate respectively (Lambert et al.,2010). Leakage flow rate can be

reduced by 111m3/h if the MNF is reduced from 158 m3/h to 47 m3/h (WRP, 2009). Table 2-4

shows the results of the previous years’ projects of pressure management.

Table 2-4: Pressure management savings from the previous projects (Meyer et al., 2009)

Area Year

commissioned

Water

savings

(Mm3/

annum)

Implementation

cost (R million)

Cost Savings

( R millions/

annum)

Payback

period

(years)

Khayelitsha 2001 9.00 2.70 55.8 0.05

Mfuleni 2007 0.40 1.50 2.50 0.60

Gugulethu 2008 1.60 1.50 9.90 0.15

Mitchell’s

plain 2008 2.40 7.70 14.90 0.52

Belhar 2009 0.20 2.50 1.20 0.02

2-22



Area Year

commissioned

Water

savings

(Mm3/

annum)

Implementation

cost (R million)

Cost Savings

( R millions/

annum)

Payback

period

(years)

Langa 2009 0.53 3.00 3.30 0.91

Eerste River 2009 1.20 2.40 7.40 0.32

Brentwood

park 2009 0.04 0.90 0.30 3.60

Figure 2-14 illustrates the suitable sites which have been identified by the City of Cape Town

(CoCT) for the implementation of pressure management schemes. Due to the limited time for

this research, it was found impossible to obtain necessary data to calculate the amount of water

that will be saved through the implementation of pressure management schemes at the proposed

sites. This is because the CoCT has not yet installed the devices to log flow and pressure at

proposed sites and it takes time to do so, therefore the required inputs for FAVAD equation were

not available during the period of this research.

Figure 2-14: Existing and proposed sites for pressure management (Ross, 2014)

Although there was no data to calculate the potential savings by pressure management

schemes, Table 2-4 showed that all the past schemes have all been successful in saving water. In

addition, all schemes have paid back within a short period after being implemented with the

2-23



longest being 3 years. Therefore, increasing pressure management schemes will increase the

amount of water that can be saved.

2.12 Water efficient devices

Water Efficient Devices (WED) are similar to standard alternatives except that they use less

water to carry out the same function. According to Still et al. (2008), in Europe, Australia, and

the USA, the use of WED such as aerated taps, dual flushing toilets, water efficient baths,

showers and basins are becoming standard. Table 2-5 shows the results of the survey which was

conducted by Still et al. (2008) on 1428 households in South Africa to investigate water use and

the level of awareness about WED of water users.

The results of the survey indicate that about 30% of the participants were interested in

using Water Efficient Devices (WED), and only 10% is already using WED. Based on these

results it can be concluded that at least 30 % of the population will adopt the use of water efficient

devices in the future and at most 90% of the population will install water efficient devices in the

long run.

Table 2-5: Survey results on the use of WED in South Africa (Still et al., 2008)

According to the study by Coulson (2014) on Liesbeek river catchment, the adoption of

Water Efficient Devices (WED) is capable of reducing the total water use of the catchment by

37%. This shows that a considerable amount of water can be saved if water efficient devices can

be adopted by the entire City of Cape Town. In this study, the potential water saving through the

adoption of WED was compared with that of greywater harvesting (GWH) and rainwater

Water efficient device Percentage of participants who

have device fitted

Percentage of those who do not

have device and would like to

install one

Aerated tap 6.7 27.7

Low flow shower 6.3 30.4

Toilet- low volume 11.6 28.5

Toilet – dual flush 9.8 32.3

Cistern displacement device 14.4 30.8

Average 9.3 29.6

2-24



harvesting (RWH) in the catchment. The amount of potable water that can be saved through the

adoption of WED outweighed that of greywater harvesting (GWH) which was 12% and rainwater

harvesting (RWH) which was 13%.

Since water that can be saved by Water Efficient Devices (WED) is potable, that gives this

option of reducing water demand an advantage over other alternatives. This is because potable

water does not have any restrictions on usage, for example greywater and rainwater cannot be

used for drinking, and a separate, expensive and complex water system is required for greywater

and rainwater use.

2.13 Tariff increase

Different countries use different structures of tariff blocks to control water demand (Still et al.,

2008). The City of Cape Town (CoCT) uses a five-step tariff block and it was introduced in 2001

(DWA, 2007b). This structure was designed in such a way that it can accommodate 6kƖ/month

of free basic water for each household in Cape Town (ibid.). Figure 2-15 illustrates historical

tariff structure for Cape Town. It can be seen that tariffs have been increasing since 2008/2009

financial year, and in 2010 a proportion of block one was shifted to block two and proportion of

block three was shifted to block four in order to reduce water demand. Furthermore, the increase

in tariffs is higher across all blocks for both 2012/13 and 2013/14.

Figure 2-15: Historical tariff block for the City of Cape Town (CoCT, 2014)

2-25



The City of Cape Town has successfully used tariff increase to reduce water demand during

periods of droughts. According to Reconciliation Strategy (2007), 30% of the tariff increase in

Cape Town has a potential to reduce up to 6 % of the total water demand. The tariff increase has

the greater impact on changing water users’ behaviour when compared with the adjustment of

meters and credit control measures (DWA, 2007b). In addition, tariff increase can also be used

to improve revenue, and use that money to fund new water schemes while the demand is being

reduced.

2.14 Greywater harvest

The study by Coulson (2014) on Liesbeeck River catchment showed that greywater can

potentially supply 12% of the catchment’s water demand. However, greywater can only be used

for two end-uses at homes, namely flushing toilets and garden watering. This is because the level

of human contact with water for toilet flushing and garden watering is very low. Therefore, health

risks associated with human contact with greywater will be minimized.

Greywater has a foul odour when it has been kept for a long time and this will be a challenge

when it is used for flushing toilets. As a result, using greywater for garden watering only will be

the best option. This will help to avoid a prolonged storage of greywater, in turn a foul odour

will be avoided. In addition, the use of greywater will provide a constant supply for garden

watering throughout the year at the cheaper cost than that of potable water.

Although, the probabilities of humans coming into contact with grey water are very low

when it is used for garden watering, there is still a need for a basic level of greywater treatment

and trip irrigation will need to be used to further minimise health risks (Christovaboal et al.,

1996;Jeppesen, 1996).

The installation and management of greywater systems are complex, and its broad scale

adoption by the City of Cape Town will become a challenge (Coulson, 2014). However, this

challenge can be simplified by using greywater for large properties such as schools, business

complexes and hospitals. Improper storage and use of greywater has serious health risks

(Christovaboal et al., 1996;Jeppesen, 1996). Therefore, there will be a need for extra care when

greywater is used by hospitals since there are more vulnerable people in hospitals.

2.15 Rainwater harvesting

The use of rainwater has less health implications when compared to greywater. In addition,

rainwater does not have a foul smell when it has been kept for long and it can be used for more

end-uses than greywater, for example washing clothes. The past studies have shown that

rainwater harvest has a potential to reduce demand for potable water by a considerable amount

as it can be seen from the previous years’ studies listed below:

2-26



The study conducted by Abdulla & Al-Shareef (2009) over twelve areas in Jordan, has

shown that a potential reduction of the demand for potable water ranges between 0.29%

to19.7%.

The Study conducted by Coulson (2014) in Liesbeek River catchment, showed that a

potential reduction of a demand for potable water can be up to 13 % of the total demand of

the catchment.

The study which was conducted by Ghisi, Montibeller & Schmidt (2006) over 62 cities in

Brazil, has shown that a potential reduction of the demand for potable water ranges between

34% and 92%.

Although the statements above proved that rainwater harvesting has a potential to reduce potable

water demand, the City of Cape Town cannot adopt rainwater harvest since it is located in a

winter rainfall region.

2.16 Private boreholes/ wellpoints

Private boreholes and wellpoints are some of the potential solutions to increase water supply and

reduce demand for potable water. Boreholes and wellpoints serve the same function, but the

difference is that boreholes are deeper and more expensive than wellpoints. This presents an

opportunity for low income and middle income residents, as they can install wellpoints instead

of boreholes.

Although private wellpoints have potential to improve water supply, they have

consequences. One of the consequences of wellpoints is that an area will run at a risk of saline

intrusion if a groundwater is over-extracted, especially in coastal areas (Mardini, 2010).

Moreover, when boreholes are randomly drilled and water is collected from many points that

will lead to a reduction in net flow of underground water and in turn affect water cycle (ibid.).

The City of Cape Town will have to put laws and regulations in place to mitigate these

consequences of using boreholes and wellpoints.

2.17 Groundwater

Groundwater forms 1.5% of the total raw water allocated to the City of Cape Town (CoCT) by

Western Cape Water Supply System (WCWSS) (WSDP, 2013). The City of Cape Town is

currently using only two aquifers, namely Albion Springs and Atlantis Groundwater Scheme

although there are at least nine aquifers in Cape Town. Seven aquifers which are currently not

used by the City of Cape are listed below:

Adamboerskraal Aquifer,

Langebaan Road Aquifer,

Elandsfontein Aquifer,

2-27



Grootwater Aquifer,

Table Mountain Group (TMG) Aquifer,

Newlands Aquifer,

Cape FlatsAquifer.

The first four aquifers are referred to as the West Coast Aquifers, and their total annual yield is

currently not known. The last three aquifers have been considered as the future water supply

schemes in the City of Cape Town and their total annual yield is estimated at 68Mm3/annum

(CoCT, 2015). Table Mountain Group Aquifer (TMG) contributes the most with the total annual

yield of 48Mm3.

Although Table Mountain Group Aquifer (TMG) is expected to have the highest yield, its

geological nature makes it challenging for the abstraction of water. There are faults which prevent

a continuous flow of groundwater and that separates a body of water into small volumes. Figure

2-16 illustrates the geological nature of Table Mountain Group aquifer.

Figure 2-16: Illustration of the geology for Table Mountain Group aquifer

(Knowles et al., 2005)

Conjunctive use is the scheme that involves injecting excess surface water into the aquifers

in winter and using it in summer. It also involves pumping groundwater into the storage facilities

of surface water to supplement supply when dam levels are low. According to the Reconciliation

2-28



Strategy Study (2007), opportunities for conjunctive use exists primarily in the West Coast

aquifers and the Breede River Valley alluvium.

As previously mentioned, climate change is expected to reduce the frequency of

precipitation and cause an intense rainfall when it occurs. In addition, evaporation rate is

expected to increase as the temperature rises. Therefore, conjunctive use schemes will come in

handy when these conditions are experienced. This is because aquifers will be used as extra

storage for excess surface water from intense precipitations. Moreover, water loss through

evaporation can be reduced by storing water underground in the aquifers.

2.18 Desalination

Desalination is the process of removing salt from seawater or brackish water to produce fresh

water. Seawater desalination is now hailed as the solution by some countries to the problem of

water shortage. However, desalination is more expensive relative to other alternatives such as

reuse of treated effluent (Koschikowski, 2011). Although desalination is more expensive

compared to other options, seawater is an unlimited and reliable water resource.

Despite the high cost to desalinate seawater, the City of Cape Town (CoCT) has considered

it as one of the future sources of water supply in Cape Town (CoCT, 2015). Since Cape Town is

located next to the sea, it will be easy to obtain seawater. According to Mabudiro presentation

(2015), the City of Cape Town is hoping to desalinate up to 160Mm3/annum in the future. This

will be a significant augmentation to the current water yield.

Desalination requires a large amount of energy. As a result, an extensive development of

desalination will increase the dependence on fossil fuel, hence increase emissions of greenhouse

gases (Kendrick, 2011). This will worsen the situation of climate change, therefore the use of

seawater should be limited to mitigate the impacts of climate change.

2.19 Treated effluent

The City of Cape Town (CoCT) has a total of 27 wastewater treatment plants, of which 9 have

the facilities to extract treated wastewater before it is released into the rivers, wetlands and sea.

This treated wastewater is further cleaned to produce treated effluent, and then transported to the

customer for irrigation. The use of treated effluent in Cape Town was introduced in 2004 (Water

Sustainable Development Plan, 2013). The distribution network for treated effluent consists of

orange pipelines, and that makes it unique from the other water distribution networks. Figure

2-17 shows a pipeline for treated effluent.

2-29



Figure 2-17: Pipeline for distribution of treated effluent (WSDP, 2011)

There are number of benefits of using treated effluent for both the City of Cape Town (CoCT)

and water users:

The demand for potable water can be reduced by substituting potable water with treated

effluent for certain water uses, for example irrigation.

The City of Cape Town can increase its revenue by selling more treated effluent, rather

than discharging treated wastewater into the sea,

Irrigation with treated wastewater is not limited during water restriction periods, therefore

this will benefit water uses,

Treated effluent is cheaper than potable water and this is a benefit to water users,

The use of treated effluent promotes diversification of water supply hence prevent

exhaustion of fresh water.

Treated effluent can be used for garden watering and flushing toilets in the domestic sector.

However, like greywater, it requires a complex system which is difficult to manage and

implement. Furthermore, a human contact with treated effluent has serious health risks and this

is one of the issues that will make the use of treated effluent challenging.

Besides using treated effluent for irrigation and indusrtial use, it can be treated further to

the standard of potable water and then augment the supply of potable water. This will facilitate

the use of treated effluent without restrictions of use, for example, it will be used for drinking

and cooking. Furthermore, a separate infrastructure to distribute this water will not be required

and there will be no health risks associated with this option.

2-30



Table 2-6 presents the potential amounts of wastewater that can be treated from some of the Cape

Town’s wastewater treatement plant in one year. In total, 31428 Mm3 of wastewater can be

treated by the City of Cape (CoCT) in one year according to Mabudiro (2015).

Table 2-6: Potential amount of treated effluent per year (CoCT, 2015)

Wastewater

treatment works

(WWTW)

Total existing

summer

reuse

(Mm3/d)

Potential

expansion of

summer reuse

(Mm3/d)

Total

potential

reuse

(Mm3/d)

% of Total

dry weather

effluent

treated

Total

potential

annual reuse

(Mm3)

Athlone 3.5 11.8 15.3 22 2423

Bellville 7.3 12.2 19.5 52 4620

Borcherds quarry 2.0 0.0 2.0 9 360

Cape Flats 6.6 9.5 16.1 17 1777

Gordonsbay 0.7 1.3 2.0 100 233

Kraaifonteen 8.6 0.4 9.0 100 2393

Macassar 3.5 7..6 11.1 35 1136

Melkbos Strand 2.2 0.1 2.2 100 360

Mitchell’s Plain 0.0 6.1 6.1 22 781

Parrow 1.5 0.4 1.9 128 308

Potsdam 32.1 12.5 46.6 95 11663

Scottsdene 6.2 2.1 8.3 100 2234

Wesflur(Atlantis) 4.8 1.6 6.4 80 1876

Weldevoelvlei 0.0 4.8 4.8 59 679

Zandvleit 1.5 4.5 6.0 15 575

Marine outfalls 0.0 0.1 0.0 0 0

Total 80.5 74.8 166.1 38 31428

2.20 Surface water development

According to the Reconciliation Strategy Study (2007), there is a number of options to increase

water supply through the development of surface water. This includes construction of new dams,

river diversions and raising of dam levels. Listed below is a list of future projects that have been

considered by the City of Cape Town to increase water supply.

Raising Lower Steenbras Dam

Construction of new Dam (Upper Campanula dam)

2-31



Lourens River Diversion

Eerste River Diversion

Voelvlei Augmentation

Construction of new dam at Misverstand

Construction of Twenty-four Rivers Dams

Construction of Waterval River Dam

Michell’s Pass Diversion

Raising Theewaterskloof Dam

Construction of Lower Wit River Dam

Wemmershoek Dam and pipeline

Upper Molenaars Diversion

Brandvlei to Theewaterskloof transfer

Refer to Appendix F for the descriptions of the future projects listed above. However, these

projects are expensive and lengthy. According to the water demand projections based on high

water requirements (HWR), the City of Cape Town will have a shortage of water by 2020 if

nothing is done, either lowering the water demand or increase the supply of water. Therefore, a

quick solution to prevent the expected water shortage is needed and this research focused on the

projects which can provide quick solutions.

3-1


Chapter 3: Procedure for WED calculations

3. Procedure for WED calculations

The chapter presents the results for low income households. The results for middle and high

income house households can be found in Appendix B. The procedure described in this chapter

for low income household was used to do calculations for middle and high income households.

The topic of water savings through the adoption of water efficient devices is often subjective, for

example when a 9Ɩ normal flush toilet is compared with an old 13Ɩ flush toilet, a 9Ɩ toilet will be

considered efficient. However, this cannot be the most efficient option since there are some

specialized flush toilets that can use as little as 1.5Ɩ per flush (Schlunke et al.,2008). To solve this

issue, water efficient devices for the end-uses were categorized into two groups namely, high

saving devices and medium saving devices.

In order to calculate the potential water savings through the adoption of water efficient

devices, average frequencies of water use and volumes required per event for each domestic end-

use were obtained from the results of the survey which was conducted by Jacobs & Haarhoff

(2004) in South Africa. These results are presented in Table 3-1.

Table 3-1: volumes and frequencies for domestic end-uses (Jacobs & Haarhoff, 2004)

Water

devices

Volume (Ɩ/ event) Frequency (per event per person/day)

Low water

use

Typical

water use

High water

use

Low water

use

Typical

water use

High water

use

Bath 39 80 189 0.22 0.24 0.9

Bathroom

basin 0.3 3.8 60 3.4 3.6 3.8

Dishwasher 15.1 25 43 0.18 0.25 0.29

Kitchen sink 0.6 6.7 73 2 2 2.1

Shower 7.6 59.1 303 0.2 0.3 0.7

Toilet normal 8 14.3 26.5 1.7 3.7 10.3

Toilet – dual

flush large 4 6 6.1 0.9 1.9 5.2

Toilet – dual

flush small 2 3 4 0.9 1.9 5.2

Washing

machine 60 113.6 200 0.1 0.3 0.6

3-2



Then, data of the amount of water use by different water efficient devices (WED) was obtained

from the results of the survey which was conducted by Still et al. (2008) and Jacobs & Haarhoff

(2004). This data is tabulated in Table 3-2.

Table 3-2: Water volume used per event by end-uses

(Jacobs&Haarhoff, 2004; Still et al., 2008)

Water efficient devices

Volume per event (Ɩ / use)

Time (min) High saving

device

Medium saving

device

Standard

device

Bath 50 65 80

Bathroom basin 2.4 l/min 6 l/min 9 l/min 0.4

Dishwasher 14 18 25

Kitchen sink 2.4 l/min 6 l/min 12 l/min 0.6

Shower 7 l/min 10 l/min 15 l/min 4

Toilet-normal 6 9 13

Toilet- dual flush large 4 6 11

Toilet- dual flush small 2.5 3 6

Washing machine 40 60 114

Table 3-3: Reduction coefficients for low income households in Cape Town

Water efficient

devices

Frequency

(use/p/d)

Standard device High Saving

device

Medium Saving

device

Device

(l/use)

Demand

(l/p.d)

Device

(l/use)

Demand

(l/p.d)

Device

(l/use)

Demand

(l/p.d)

Bath 0.2 80 17.6 50 11 65 14.3

Bathroom basin 3.4 3.6 12.2 1 3.3 2.4 8.2

Dishwasher 25 0 14 0 18 0

Kitchen sink 2 7.2 14.4 1.4 2.8 3.6 7.2

Shower 60 0 28 0 40 0

Toilet-normal 2 13 26 6 12 9 18

Toilet- dual flush

large 11 0 4 0 6 0

Toilet- dual flush

small 6 0 2.5 0 3 0

3-3



Water efficient

devices

Frequency

(use/p/d)

Standard device High Saving

device

Medium Saving

device

Device

(l/use)

Demand

(l/p.d)

Device

(l/use)

Demand

(l/p.d)

Device

(l/use)

Demand

(l/p.d)

Washing machine 114 0 40 0 60 0

Total 70.2 29.1 47.7

Coefficients 0.41 0.67

The reduction coefficients for inefficient water use in domestic sector were then calculated using

the information in Table 3-1 and Table 3-2. In this research it was assumed that residents in low

income areas do not have dishwashers, showers and washing machines. Therefore, frequencies

for these devices were equated to zero.

To calculate reduction coefficients, the frequency of use for each water device was

multiplied by a volume required per event to get a daily demand. This calculation was done for

standard, high saving and medium water saving devices. The total demand for high and medium

water saving devices were each divided by the total demand of standard devices to get reduction

coefficients. Table 3-3 presents the reduction coefficients for low incomes household in Cape

Town. The same calculations were also done for middle and high income households, and the

tables for these calculations can be found in Appendix B.

Table 3-4 presents a summary of the calculated reduction coefficients for low, middle and

high income households. The average coefficients for high and medium water efficient devices

was then calculated.

Table 3-4: Average reduction coefficients for high and medium saving devices

Household income level High saving device Medium saving device

High income 0.41 0.62

Middle income 0.40 0.61

Low income 0.41 0.68

Average 0.41 0.64

The average coefficients were then used to determine the annual reduction of water for the

City of Cape Town at three adoption rates of water efficient devices. First adoption rate was

when 30% of the Cape Town’s population have water efficient, second adoption rate was when

50% of the population installed water saving devices and the last one was when the whole

community of Cape Town have water efficient devices. These adoption rates were chosen based

on the findings of the survey conducted by Still et al. (2008) which were discussed in Chapter 2.

3-4



Finally, an estimation of the amount of water reduction was obtained by multiplying the annual

domestic water demand for Cape Town by a reduction coefficient and the percentage of people

using devices (high and medium saving devices). For example, if the average water use for a

particular low income household was 6kƖ/month and medium saving devices were adopted, then

water use would reduce to 4.1kƖ/month.

4-1


Chapter 4: Results and Discussion

4. Results and discussion

This chapter presents the findings of the research. It starts off by providing an overview of the

current situation of the City of Cape Town regarding potable water supply. Then, it continues by

providing the results of the proposed solutions. The proposed solutions are grouped into two

categories, namely water demand reduction and water supply increase. Finally, the results of the

combined effects of the two solutions are provided. Figure 4.1 is a graphical summary of how

this chapter is structured.

Figure 4.1: Structure for chapter four

The situation of water supply in the City of Cape Town

The current water balance.

Future projections of water demand and supply.

Impacts on the City of Cape Town’s water supply.

What needs to be done to solve the City of Cape Town’s water

crisis?

Reducing water demand

How can this be achieved?

How much water can be saved?

Results after implementing

water reduction measures.

Increasing potable water supply

How can this be achieved?

By how much potable water needs to be

increased to ensure sufficient supply in 2040?

Results after increasing water supply.

Solutions

Combined results of water demand

reduction and water supply increase.

4-2



4.1 The situation of the city of Cape Town’s water supply

Figure 4.2: current water balance for Cape Town

4-3



Figure 4.2 illustrates the current water balance for the City of Cape Town (CoCT). The Western

Cape Water Supply System (WCWSS) currently provides the City of Cape Town with 399Mm3

of potable water per annum at 90% level of water supply assurance. This water is distributed to

different water use sectors as shown in Figure 4.2. Then, about 62.5% is discarded into the

sewage system as wastewater and then transported to nearby wastewater treatment works

(WWT). This wastewater is then treated before released into the environment from the

wastewater treatment works, to reduce harm to the environment. About 13.6% of the treated

wastewater is further treated to become treated effluent, and then used for irrigation. The

remaining 37.5% of the supplied potable water that is not discarded as wastewater, it is used

outdoors, and some of it is lost into the atmosphere as a result of evapotranspiration. The rest of

the other water percentage infiltrates into the soil due to pipe leakages and recharge groundwater.

(Water Conservation and Water Demand Management Strategy, 2015)

Figure 4.3: Projections of Cape Town's water demand

250

300

350

400

450

500

550

600

650

700

750

2000 2005 2010 2015 2020 2025 2030 2035 2040

Annual

Wat

er V

olu

me

(Mm

3)

Years

Water suppy to CoCT by WCWSS Impact of climate change

Actual trend in the previous years Projected trend for high water requirement

Projected trend for low water requirement

4-4



The City of Cape Town uses water demand growth rates of 2% and 3.38% per annum to make

projections for Low Water Requirements (LWR) and High Water Requirements (HWR)

respectively. These growth rates were used in this research to make water demand projections

from 2014 to 2040, and the results are shown in Figure 4.3. The figure shows that Cape Town

will experience a shortage of water in 2021 if water demand follows HWR trend (yellow line),

but if water demand follows LWR trend (green line), Cape Town will experience water shortage

in 2024. However, it was shown in Figure 2-11 that the City of Cape Town is expecting a shortage

of water to occur in 2020 based on HWR trend. This difference in years of water shortage

occurrence is because the City of Cape Town used the year 2013 as the baseline for the

projections, and in this research 2014 was used as the baseline. The reason for using the year

2014 as the baseline is because that is the year in which the last actual water demand was

measured by the City of Cape Town. To be more accurate, the City of Cape Town should expect

water shortage by 2021 not 2020, only if nothing is done on high water requirements.

This research has found that although population growth and economic growth contribute

to water demand increase, the biggest driver of water demand growth is the rise in the standard

of living. This is because people tend to consume more stuff when their standard of living goes

up (Parkin et al., 2008). Therefore, water demand was decided to be reduced by decreasing water

losses and the total amount of inefficient water use.

As mentioned in Chapter 2, the total water loss currently accounts for 15.8% of the total

water demand for the City of Cape Town (CoCT). The Unavoidable Annul Real Loss (UARL)

for the Cape Town is 15% of the total water demand. Therefore, the City of Cape Town can

economically reduce the total water loss by 0.8% of the total water demand. This can be achieved

through the implementation of the Water Demand Management strategies which were mentioned

and discussed in chapter 2.

Since the rising standard of living leads to a higher water usage, Water Demand

Management (WDM) strategies need to be implemented to reduce the growth of water demand.

For the purpose of this research, the amount of inefficient water use that can be reduced through

the adoption of Water Efficient Devices (WED) in the City of Cape Town was modelled. The

inefficient water use was considered only in the domestic sector, as it accounts for 47.6% of the

total water demand. This is because a large percentage of water saving can be realised by

reducing inefficient water use in the domestic sector.

4.2 User education and campaign programs

It was found that user education programs play a very important role in reducing water demand.

This is because, often the well-designed projects for reducing water demand do not succeed

because community may have not been included into the process (McKenzie, 2014). These

programs help to teach people about and make them aware of the new strategies of saving water.

For example, according to Still et al. (2008), about 60% of the South African population is not

4-5



aware of the water efficient devices. This is one of the reasons the adoption rate of water efficient

devices is low in South Africa, with only 10% of the population using the devices.

Education programs need to be expanded and lead the implementation of the new

strategies. This will help to change human behaviour regarding water usage, and increase

awareness of the importance of saving water in the community. Furthermore, this will increase

the knowledge of the community on how to save water, because people cannot be able to save

water if they do not see the importance and know to save water.

4.3 Results of water demand reduction

Figure 4.4: Projections for high water requirements after water demand reduction

250

300

350

400

450

500

550

600

650

700

750

2000 2005 2010 2015 2020 2025 2030 2035 2040

Annual

Wat

er v

olu

me

(Mm

3)

Years

Water supplied to CoCT by WCWSS Impact of climate change

Actual trend in the previous years Projected trend of high water requirements

30% WED adoption 50% WED adoption

90% WED adoption Final results

4-6



Figure 4.4 shows the results of high water demand after the adoption of water saving devices and

reduction of real water loss. The dotted-lines show the trends that will be followed by unrestricted

growth in water demand. When the results of water saving devices were modelled, it was

assumed that it will not be possible for all residents in Cape Town to install the devices at the

same time. Therefore, three adoption rates namely 30%, 50% and 90% were used over time.

According to the assumptions of this research, it can take 3 years to install water saving

devices to 30% of the Cape Town’s population, if the City of Cape Town can be committed to

this idea. It was further assumed that the whole population will have water saving devices by

2023, which is 8 years from now. Furthermore, it was assumed that by 2025 water distribution

network will be losing only 15% of the total water demand which is unavoidable water loss for

the City of Cape Town.

It can be seen in Figure 4.4 that the current amount of available potable water supply is

decreasing constantly due to the impacts of climate change. This is represented by a red dash

line, and the predictions of this trend were made by the City of Cape Town based on the

assumption that climate change will reduce the current system’s yield by 5% in 25 years. The

impacts of climate change include, inter alia, high rate of evaporation due to the increase in

average temperature and a decrease in rainfall frequency. This decline in the total yield from the

current water sources will shortened the time that will take the increasing water demand to reach

the available supply by a year.

In contrast to the climate change projections shown in Figure 4.4, some research has

indicated that the impacts of climate change on the system yield is not a steady decline but rather

a fluctuating trend (Reconciliation Study, 2011). Therefore, in order to provide a more accurate

predictions of the impact of climate change on the available fresh water resources, a detailed

modelling is required, and that is beyond the scope of this research.

Figure 4.4 shows the same water demand of approximately 350Mm3/annum in 2017 and

2025 after the implementation of demand reducing strategies. During the period between these

years, there is a fluctuation of water demand. This is because water efficient devices reduce a

certain amount of inefficient water use after the installation while there is continuous increase in

water demand. According to the projections in Figure 4.4, the adoption of water saving devices

and reduction of non-revenue water will prevent water demand growth between 2017 and 2025.

In turn, the need for additional water supply source will be extended by 7 years, from 2021 to

2028.

Based on the new projections, water demand is now expected to be 577Mm3 in 2040, which

is 178Mm3 above the total water yield from the current water sources. This water demand can be

reduced further by expanding the adoption of water inefficient devices to other sectors such as

industrial and commercial sectors, and not limiting water efficient devices to indoor use. The

solutions that have been provided in this report so far, have the potential to decrease water

demand in 2040 from 747Mm3 to 577Mm3, and this will result in a water saving of 170Mm3.

4-7



As it can be seen in Figure 4.4, there will now be a water deficit after 2028, therefore additional

water sources that can ensure water security until 2040 were investigated instead of decreasing

water demand by implementing more demand reducing interventions. This is because climate

change, on the other hand, is causing a decline in the available amount of fresh water resources.

As a result, even if water demand remains constant the change in climate will cause a water

shortage. The result of additional water sources are provided in the following section.

The population of South Africa is expected to start declining in the early 2030s, mainly

due to lower fertility rate and the impact of AIDS epidemic (CoCT, 2010). This will in turn result

in a decline of water demand growth rate in the City of Cape Town. This is because the growth

rate of water demand depends on the rising standard of living and population growth. Therefore,

the results that are shown in Figure 4.4 might change around the year 2030 when the growth rate

of water demand decreases.

Figure 4.5: Projections for low water requirements after reducing water demand

250

300

350

400

450

500

550

2000 2005 2010 2015 2020 2025 2030 2035 2040

Wat

er v

olu

me

(Mm

3)

Years


Actual trend in the previous years Projected trend of low water requirents

Impact after 30% WED adoption rate Impact after 50% adoption rate

Impact after 90% WED adoption rate Final results

4-8



Figure 4.5 shows the projections of low water requirements trend. The City of Cape Town uses

2% per annum as the growth rate for the projections of low water requirements. The 2% per

annum growth rate was therefore used in this research. The same procedure which was explained

above for the projections of high water requirements in Figure 4.4, was used to make the

predictions shown in Figure 4.5 for low water requirements. This represents the lower bound of

water demand projections for the City of Cape Town.

Household’s water efficient devices were assumed to first be adopted in 2017 by 30% of

the population in Cape Town. Then, 50% and 90% of the population were assumed to install the

devices by 2019 and 2023 respectively. Furthermore, by 2025, it was assumed that 100% of the

Cape Town’s population will have household’s water efficient devices and the City of Cape

Town will have achieved the reduction of water loss to 15% of the total demand. This is the

reason Figure 4.5 shows a fluctuation of water demand between 2017 and 2025, then the water

demand continues to increase after the fluctuation. Between the year 2017 and 2025, there is a

total decrease in water demand, which is the amount of inefficient water use.

The new projections after reducing inefficient water use show that water deficit will now

be experienced in 2036 instead of 2025. This postpones the need for additional water sources by

a period of 10 years. However, water deficit would be required by 2039 in the absence of climate

change. As a result, climate change has shortened the time to experience water deficit with about

3 years. Moreover, in the year 2040, water demand will be 320Mm3 above the expected water

yield of that year. Further water demand reduction measures will need to take place or additional

water sources will need to be found by 2040.

4.4 Options for additional water supply

A number of potential options to increase the total water yield of the City of Cape Town were

investigated, and discussed in Chapter 2. The pros and cons of these options were evaluated, and

the approach of multi-criteria analysis was used to choose the best three options in this chapter.

The potential options to increase water yield of the current water sources that were considered in

this research are listed below, and each option was assigned a number which represented it in the

multi-criteria analysis table.

1. Greywater harvesting

2. Rainwater harvesting

3. Reuse treated effluent

4. Treat effluent to the standard of potable water

5. Add more aquifers to the system

6. Promote the use of boreholes/well-points

7. Desalinate sea water

4-9



Table 4.1 presents the results of the multi-criteria analysis. To carry out the analysis, negative

impacts of each option were scaled out of 10. The higher the scale value the more negative impact

an option has. The important issues that should be considered before the implementation of each

option were also investigated, and they are presented in the Table 4.1. Furthermore, each

considered issue was assigned a level of importance between 0-10 based on the judgement and

knowledge of the researcher.

Table 4.1: Multi-criteria analysis table

Issues

Alternatives Level of

importance

1 2 3 4 5 6 7

Environment/health risks 9 2 9 1 1 3 7 7.5

Options with low annual

yield 6 8 2 2 4 9 1 9

Complexity to implement 1 5 8 2 2 2 2 6

Option that are expensive

to implement 7 4 7 6 4 4 9 8

Negative impacts:

∑Impact*importance 225.5 149 189.5 85.5 97.5 147.5 145.5

The positivity of each option was calculated by subtracting the total negative impact of

each option from 400, which is the maximum negativity an option can have. The costs of the

alternatives were regarded as negativity; the more expensive the alternative is, the more negative

impact it has. The positivity values for all options are presented in Table 4.2 together with the

rankings. The first three options with the highest positivity values, were considered as the best

options to supplement the total water yield in order to avoid the expected water shortage in Cape

Town.

4-10



Table 4.2: Ranking of the alternatives' positive impacts

Alternatives Positivity Ranks

Greywater harvesting 174.5 7th

Rainwater harvesting 251 5th

Reuse treated effluent 210.5 6th

Treat effluent to potable water 314.5 1st

Use more aquifers 302.5 2nd

Wellpoints/boreholes 252.5 4th

Seawater desalination 254.5 3rd

4.5 Treat effluent

The City of Cape Town treats about 214Mm3 of wastewater per annum. Most of the treated

wastewater is discharged into the sea while about 13.5% of the treated effluent is used for

groundwater recharge and irrigation, mostly golf courses. In addition, it was found that the City

of Cape Town has the potential to increase the amount of treated effluent reuse by 31Mm3 per

annum. This additional amount of treated effluent can be used to offset the need of potable water,

or it can be treated to the standard of treated potable water, and supplement the total water yield.

The results of multi-criteria analysis indicated that it will be more economical to treated

wastewater to the standard of potable water than reusing treated effluent. The water will be able

to use the existing potable water infrastructure for distribution, and hence save additional costs

of constructing separate infrastructure for transportation and safe irrigation systems. Moreover,

this will significantly reduce health risks.

This research therefore suggests that the City of Cape Town upgrades its wastewater

treatment plants, and reuse 31Mm3 of the treated effluent as potable water per year. This will

help to save the costs and prevent water deficit.

4.6 Seawater desalination

Desalinating seawater is expensive compare to the purification of fresh water and wastewater.

However, the results of multi-criteria analysis ranked seawater desalination as the third best

option compared to the other potential options which were considered in this research.

Furthermore, it was mentioned in chapter 2 that the City of Cape Town is aiming at desalinating

160Mm3 per annum of seawater in the future. This amount will increase the current total water

4-11



yield of Cape Town by 47% to 599Mm3 per annum. This will substantially improve the water

supply of the City of Cape Town.

Some of the benefits of desalinating seawater is that there are no health risks posed to the

users, and desalinated water can be distributed through the existing infrastructure of potable

water. In addition, seawater is a reliable and unlimited water resource. This will ensure that the

City of Cape Town will not be affected during drought periods, since climate change is expected

to cause droughts in the future. However, some researchers claim that the use of seawater will

exacerbate the situation of climate change because that will increase the use of fossil fuel.

4.7 Groundwater

Figure 4.6: Potential contribution by each additional water source

The results of multi-criteria analysis show that Table Mountain Group aquifer, Newlands aquifer

and the Cape Flats aquifer have a high potential to improve the City of Cape Town’s water

supply. Furthermore, the use of these aquifers is regarded as the second best option compare to

the other options that were considered in this research.

Currently the City of Cape Town uses two aquifers, namely, Albion Springs and Atlantis

Groundwater Scheme. These aquifers account for 1.5% of the potable water supplied to the City

of Cape Town (WSDP, 2013). The Table Mountain Group aquifer, Newlands aquifer and Cape

68

160

31

0

20

40

60

80

100

120

140

160

180

Aquifers Desalinated seawater Reuse treated effuent

Vo

lum

e (

Mm

3p

er

ann

um

)

Proposed options

4-12



Flats aquifer will therefore increase the use of groundwater in the Cape Town. The total potential

annual yield of these three aquifers is estimated at 68Mm3 per annum. These aquifers will

increase the current annual water yield by 17% to 467Mm3 per year.

The Table Mountain Group (TMG) aquifer has a considerably higher annual yield compare to

the other two aquifers. Its annual yield is estimated at 40Mm3. However, the abstraction of

groundwater for TMG aquifer is not easy. This is due to the geological nature of the area in which

it is located. This area is still under the investigations to optimize the abstraction from the Table

Mountain Group aquifer.

Lastly, it was found that there are four more west coast aquifers which are not being used

by the City of Cape Town. The annual yield volumes of these aquifers are currently not known.

They are located close to the rivers, and this rise the opportunity for conjunctive use. Conjunctive

use is a process of transferring water between the aquifers and dams. This will help to provide

extra storage of water during winter when there is a high rainfall. The water stored in these

aquifers will then be transferred back to supplement dams during dry months of summer.

Figure 4.6 shows the breakdown of the water contributed by each proposed option to the

current water system. The total volume of these options is the solution to increase water Cape

Town’s annual water yield.

4.8 Future projections of water demand

Figure 4.6: Projections of water demand after including additional sources

250

300

350

400

450

500

550

600

650

700

750

2000 2005 2010 2015 2020 2025 2030 2035 2040

Wat

er v

olu

me

(Mm

3 )

Years



Projected trend of low water requirents Aquifers

Seawater desalination Reuse treated effluent

4-13



Figure 4.7 shows the projections of unrestricted low water requirements and high water

requirements with an increased annual water yield. The total water supplied to the City of Cape

Town has been increased by 259Mm3 per annum. However, if the increase in water demand

follows high water requirement’s trend, there will be a shortage of water by the year 2036; but if

the increasing water demand follows the trend of low water requirement, water deficit will be

experienced after the year 2040.

To ensure water security in the City of Cape Town until 2040, water demand should be

controlled to follow low water requirements’ trend. This can be achieved by implementing Water

Demand Management (WDM) strategies, to reduce the amount of water use. If low water

requirements cannot be maintained, the City of Cape Town will need more water sources by

2036 as shown in Figure 4.7. The projected high water requirement will be 747Mm3 per annum

in 2040, and that is 112Mm3 greater than the proposed water supply increase. Therefore, to avoid

water shortage before 2040 by increasing water supply, the City of Cape Town needs find

additional water sources that can supply 371Mm3 per annum unless the demand decreases.

4.9 Final results

Figure 4.7: Final projections for high water requirements

250

300

350

400

450

500

550

600

650

700

750

2000 2005 2010 2015 2020 2025 2030 2035 2040

Wat

er v

olu

me

(Mm

3)

Years



30% WED adoption 50% WED adoption

90% WED adoption Final results

Aquifers Seawater desalination

Reuse treated effluent

4-14



Figure 4.8 illustrates the final high water requirements’ projections after increasing total water

supply and reducing inefficient water use in Cape Town. These projections were carried out to

check the situation of water supply in 2040 after implementing the suggested solutions which

intended to ensure water security by 2040. It can be seen that the projected water demand is lower

than the total water supply in 2040, therefore, if the proposed solutions are implemented, the City

of Cape Town will not experience water crisis by the year 2040.

When the projections were done, the time required to put each proposed solutions into

effect was taken into consideration. The estimations of the time required to implement each

solution were given by Mr Colin Mabudiro (Head of Water Demand Management and

Operations for the City of Cape Town) during the interview.

As it can be seen in Figure 4.8, it was assumed that additional aquifers will be used by

2027, which is 12 years from now. In addition, more water will come from treated effluent which

is assumed to happen in 16 years from now. Lastly, the facilities to desalinate seawater of about

160Mm3 per annum are assumed to be completed by the year 2034, which is 19 years from 2015.

In overall, the City of Cape Town is assumed to have additional water supply of 259Mm3 per

annum in 19 years’ time.

The water demand is projected to be 747Mm3 per year in 2040 for unrestricted water

demand growth. The implementation of the suggested solutions to reduce the amount of

inefficient water use will help to decrease water demand in 2040 to 577Mm3. In addition, the

implementation of these solutions will postpone the time of water shortage by 7 years, and this

will enable additional water sources projects to be completed before the City of Cape Town

experience water deficit. Lastly, after the implementations of all the proposed solutions, a

shortage of water will now be expected to happen in the year 2047. The proposed solutions will

therefore help to extend water supply of the City of Cape Town by 32 years.

Figure 4.8: Final projections for low water requirements

250

300

350

400

450

500

550

2000 2005 2010 2015 2020 2025 2030 2035 2040

Wat

er v

olu

me

(Mm

3)

Years

Water supplied to CoCT by WCWSS Impact of climate changeActual trend in the previous years Projected trend of low water requirentsImpact after 30% WED adoption rate Impact after 50% adoption rateImpact after 90% WED adoption rate Final resultsAquifers

4-15



Figure 4.9 illustrates the projections of low water requirements after reducing the amount of

inefficient water use and increasing water supply. The trend of low water requirements shows

that, a first water deficit will be experienced in 2036 if only water use reduction measures are

implemented. Furthermore, in 2040, water demand will be 32Mm3 greater than the available

supply. As a result, additional water sources had to be added into the system to increase the

supply. The additional sources consists of only aquifers namely, Table Mountain Group,

Newlands and Cape flats aquifers. The seawater desalination and treated effluent were not

considered here since the demand is low, and water security can be achieved through the use of

ground water alone.

The reason for choosing aquifers over seawater desalination and effluent reuse is the costs

associated with water purification. In additional, new big infrastructures are not required for

using groundwater as compared to the other two options. As a result, the City of Cape Town will

save money by choosing groundwater.

Since the water demand is still increasing, seawater desalination and reusing treated

effluent will be needed in the future, if no better alternatives have been found. Furthermore, by

comparing the results of high water requirements (HWR) and low water requirements (LWR), it

can be seen that a lot of effort will be needed if water demand follows HWR trend. Therefore,

this can be avoided by ensuring that water demand follows LWR trend by further implementing

water demand management strategies.

The water balance of the City of Cape Town for the year 2040 was done for only high

water requirements, which is the worst-case scenario. Figure 4.10 illustrates the predicted 2040

water balance after the implementation of the suggested water solutions. From the figure, it can

be seen that only 79Mm3 of the desalinated seawater will be needed to supplement water supply,

if all the other proposed solutions are used to their full potential. This will save the costs of

desalinating extra 81Mm3 per annum. In addition, water supply in the City of Cape Town will be

diversified. This will ensure that water supply in Cape Town is sustainable and resilient since

there will be alternative supplies. Finally, the 2040 water balances show that Cape Town will be

water secured if the proposed solutions can be implemented by the City of Cape Town.

4-16



Figure 4.9: Cape Town's 2040 water balance

5-1


Chapter 4: Conclusions and Recommendations

5. Conclusions and recommendations

Literature review showed that the current water management interventions are not sustainable in

the long term. Therefore, the alternative water management approaches need to be put in place.

These approaches include sustainable urban water management approaches such as water

sensitive urban design (WSUD), total water cycle management (TWCM) and integrated urban

water management (IUWM).

South Africa is a semi-arid country with annual rainfall of 450mm that is lower than

world’s average rainfall of 860mm. However, the average amount of water use per capita per

day in South Africa is 62Ɩ more than the world’s average. This shows that there is amount of

water that is used inefficiently is South Africa. Therefore, there is a potential of decreasing

potable water demand by reducing inefficient water use.

This research has shown that Cape Town’s water resources are threatened by a rapid

increase in water demand and a decline of annual water yield from current water sources due to

the impact of climate change. However, there is still a number of solutions that can be

implemented to combat water crisis that is facing the City of Cape Town. This can be achieved

by either increasing water supply through additional water sources or decreasing water demand.

The City of Cape Town has been successful in reducing water demand in the previous years

through Water Conservation and Water Demand Management (WC/WDM) initiatives. However,

most of these initiatives have not been implemented to their full potential while other WC/WDM

initiatives have not yet been implemented at all. Therefore, it is concluded that there is a

significant amount of water demand that can still be reduced by further implementing WC/WDM

initiatives depending on the implementation of the intiatives.

It is was found that about 60% of the South African population is not aware of water

efficient devices, and only 10% of the population is already using water efficient devices.

Furthermore, the idea of using water efficient devices to reduce demand is not mentioned in the

future plans of the City of Cape Town which are outlined in the Reconciliation Strategy report

(2008). As a result, the potential water saving through the installation of water efficient devices

throughout the households of Cape Town was calculated by using Residential End-Use Model

(REUM). It was found that 100% adoption rate of water efficient devices in domestic sector will

reduce total water demand by 20%. This will postpone the need for additional water sources by

6 years from 2021 to 2027 for high water requirements. In addition, the projections for high water

requirements show that water demand will be 149Mm3 less than unrestricted water demand in

the year 2040. If the City of Cape Town manages to keep water loss at unavoidable real loss,

then 22.8% water demand will be saved per year.

The City of Cape Town is therefore recommended to consider the adoption of water

efficient devices. By adopting water efficient devices, the demand of water will be reduced and

the expected water shortage which is expected to happen in 2021 will postponed. This will

5-2



therefore give the City of Cape Town time to find the new additional water sources to augment

the current water supply.

It was found that the City of Cape Town is reusing 13.6% of the treated wastewater and

the rest is discharged away. Furthermore, only 1.5% of Cape Town’s water demand comes from

groundwater. It was therefore concluded that Cape Town’s water supply is not diversified as it

relies mainly on surface water. To increase water supply, it will be wise to increase amount of

treated effluent and groundwater that is currently used, instead of finding additional surface water

sources. For the purpose of this research, the amount of groundwater that is used is suggested to

be increased by 68Mm3/annum and treated effluent to be increased by 31Mm3/annum. In

addition, the outcomes of multi-criteria analysis which was carried out in this research, showed

that seawater desalination has a high potential of improving the future water supply in Cape

Town despite high costs of desalination process. This research therefore support the City of Cape

Town to desalinate 160Mm3/annum as one of its future plans. This will help to avoid the

exhaustion of surface water and improve water diversification in Cape Town.

Although the City of Cape Town is considered threatened by a shortage of water in the

future, the findings of this research showed that there are still ways to ensure water security in

Cape Town. The research suggests the City of Cape Town to reduce its water demand through

installation of water efficient devices and reduction of water losses. In addition, the City of Cape

Town is suggested to increase its water yield by desalinating seawater, reusing treated effluent

and adding more aquifers to the system, namely Table Mountain Group, Newlands and Cape

Flats aquifers. By implementing these suggested solutions, the City of Cape Town will achieve

22.8% of water demand reduction and increase its annual water yield by 259Mm3. This will

therefore ensure water security until 2040 and result in a water surplus of 81Mm3 in 2040.

The project has successfully achieved its goal of searching for potential solutions to ensure

water security in Cape Town until 2040. Furthermore, this research showed that the City of Cape

Town has the potential to prevent the expected water deficit.

Recommendations for further research

The following recommendations were made to improve the suggested solutions to Cape Town’s

water crisis:

In this research, the amount of water that can be saved through the adoption of water

efficient devices was calculated for domestic sector only. For future research, calculate the

amount of water savings when water efficient devices have been adopted by other water

sectors such as commercial, industrial and agricultural sectors.

The City of Cape Town believes that its total water loss cannot be reduced to below 15%

of the total demand economically, while some countries like Singapore has total loss of

about 2%. So investigate ways in which Cape Town can reduce its unavoidable annual real

losses in order to decrease the total water demand.

5-3



Although seawater desalination is recommended in this research, the cost of desalination

process is relatively higher than that of the other additional water sources. Therefore, search

for cheaper additional water source that can replace 160Mm3 of water from the sea.

This research has shown that the City of Cape Town has the potential to ensure water

security until 2040. Therefore extend the projections of the suggested solutions in the future

project to 2060.

4


References

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supply in Jordan. Desalination, 243(1–3): 195-207.

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Flack, J. (1981). Residential Water Conservation. Journal of the Water Resources Planning

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8


Appendices

Appendix A: ECSA exit level outcomes

Problem solving: ELO 1

Cape Town is facing a considerable challenge of water scarcity, and according to the City of

Cape Town’s projections, there is an expectation of water shortage by 2020. Therefore, the main

goal of this research was to investigate solutions that can ensure water security in Cape Town

until 2040. The objectives of this research were to gain a better understanding of the extent of

the problem, and find solutions that can be applicable to Cape Town. These solutions were

critically evaluated and they were presented in an appropriate form, which includes graphs, tables

and in writing. The student managed to find an effective solution that can eliminate the possibility

of water shortage in Cape Town during the period between 2015 and 2040; this can be seen in

the future projections made by the student. The student has therefore met this requirement.

Application of scientific and engineering knowledge: ELO 2

The Residential End-Use Model (REUM) provided by Jacobs & Haarhoff (2004) was used to

analyse and calculate the potential water savings for residential properties in Cape Town. Further

calculations were done on Microsoft excel to estimate the total water savings by the suggested

solutions. In additions, more calculations were done to get the future projections of water

demand. Some of the concepts of physics and chemistry were also used in this research, for

example, the relationship between temperature and evaporation was used predict the impact of

climate change on water resources. The relationship between water pressure and leakage rate was

discussed, and used to explain why more water is lost when there is a high pressure in pipes,

especially at night. Therefore the student has met this requirement.

Investigation, experiments and data analysis: ELO 4

The research proposal was written in the beginning of this research project. This proposal

included method statement, preliminary literature review, and justification of the research as well

as the planning of executing the research. The literature review was again done in the beginning

of the research and the findings of the literature were critically evaluate. This research did not

have experiments therefore data that was already available was used. This data was analysed

first, and appropriate software (Excel) was used to do calculation and generate graphs for

interpretation of results. Therefore the student has met this requirement.

9


Appendices

Engineering methods, skills and tools, including IT: ELO 5

Engineering methods such as multi-criteria analysis were used for decision making in this

research. Computer application which was used for this research is excel spreadsheet, and it was

used to carry out all the long calculations correctly. Judgment skills of the student were also used

to assess the results and make some decisions. Therefore the student has met this requirement.

Professional and technical communication: ELO 6

The findings of this research were communicated effectively for non-technical and technical

audiences in the form of report and e-portfolio. The appropriate structure, style and language

were used for communication. Figures and tables were used to present the results in a clear and

appropriate way.

Individual team and multidisciplinary working: ELO 8

This research project was an individual work, therefore, the student worked alone and managed

to complete and submit the work on time. Therefore the student has met this requirement.

Independent learning activity: ELO 9

The student learned the research topic independently, with the guidance of his supervisor (Prof.

Neil Armitage). Literature review was done and a number of interview with the City of Cape

Town’s professional in the DWS and some of the academics in UCT were conducted. The

information gained through self-learning was used in this research. Therefore the student has

met this requirement.

10


Appendices

Appendix B: Water Saving Devices’ coefficients

Table B-1: Calculations of water demand reduction coefficients (High income households)

Water

efficient

devices

Current case High saving case Medium saving case

Frequency

(use/p/d)

Device

volume

(Ɩ/use)

Demand

(Ɩ/p.d)

Device

volume

(Ɩ/use)

Demand

(Ɩ/p.d)

Device

(Ɩ/use)

Demand

(Ɩ/p.d)

Bath 0.3 80 24 50 15 65 19.5

Bathroom

basin 3.6 3.6 12.96 0.96 3.456 2.4 8.64

Dishwasher 0.29 25 7.25 14 4.06 18 5.22

Kitchen sink 2.1 7.2 15.12 1.4 2.94 3.6 7.56

Shower 0.5 60 30 28 14 40 20

Toilet-

normal 0 13 0 6 0 9 0

Toilet- dual

flush large 1.5 11 16.5 4 6 6 9

Toilet- dual

flush small 2 6 12 2.5 5 3 6

Washing

machine 0.3 114 34.2 40 12 60 18

Total 152.0 62.5 93.9

Coefficient 0.41 0.62

11


Appendices

Table B-2: Calculations of water demand reduction coefficients (Middle income

households)

Water

efficient

devices

Current case High saving case Medium saving case

Frequency

(use/p/d)

Device

volume

(Ɩ/use)

Demand

(Ɩ/p.d)

Device

volume

(Ɩ/use)

Demand

(Ɩ/p.d)

Device

volume

(Ɩ/use)

Demand

(Ɩ/p.d)

Bath 0.24 80 19.2 50 12 65 15.6

Bathroom

basin 3.6 3.6 12.96 0.96 3.456 2.4 8.64

Dishwasher 0.25 25 6.25 14 3.5 18 4.5

Kitchen sink 2 7.2 14.4 1.4 2.8 3.6 7.2

Shower 0.3 60 18 28 8.4 40 12

Toilet-

normal 13 0 6 0 9 0

Toilet- dual

flush large 1.5 11 16.5 4 6 6 9

Toilet- dual

flush small 2.1 6 12.6 2.5 5.25 3 6.3

Washing

machine 0.2 114 22.8 40 8 60 12

Total 122.7 49.4 75.2

Coefficient 0.41 0.61

Table B-3: Summary of water demand reduction coefficients

Income levels High water saving devices Medium water saving devices

High income 0.41 0.62

Middle income 0.4 0.61

Low income 0.41 0.68

Average 0.41 0.64

12


Appendices

Appendix C: Water demand projections

Table C-1: Proportions of domestic water requirements (Units in Mm3/annum)

Total high water

requirements (Mm3)

Total low water

requirements(Mm3)

Domestic high water

requirements(Mm3)

Domestic low water

requirements(Mm3)

330.0 330 154.1 154.1

341.2 336.6 159.3 157.2

352.7 343.3 164.7 160.3

364.6 350.2 170.3 163.5

376.9 357.2 176.0 166.8

389.7 364.3 182.0 170.1

402.8 371.6 188.1 173.6

416.5 379.1 194.5 177.0

430.5 386.6 201.1 180.6

445.1 394.4 207.9 184.2

460.1 402.3 214.9 187.9

475.7 410.3 222.1 191.6

491.8 418.5 229.7 195.4

508.4 426.9 237.4 199.4

525.6 435.4 245.4 203.3

543.3 444.1 253.7 207.4

561.7 453.0 262.3 211.6

580.7 462.1 271.2 215.8

600.3 471.3 280.3 220.1

620.6 480.7 289.8 224.5

641.6 490.4 299.6 229.0

663.3 500.2 309.7 233.6

685.7 510.2 320.2 238.3

708.8 520.4 331.0 243.0

732.8 530.8 342.2 247.9

757.6 541.4 353.8 252.8

783.2 552.2 365.7 257.9

Note: Total water requirements represent water demand for the City of Cape Town. In addition,

total high water requirements were multiplied by 46.7% to obtain domestic water requirements.

13


Appendices

Appendix D: Water demand reduction for domestic

sector

Table D-1: Water demand reduction at 30% adoption rate (Units in Mm3/annum)

Projections for high water requirements

on 30% adoption rate

Projections for low water requirements on

30% adoption rate Years

Current

case

High

saving

Medium

saving

New

demand

Current

case

High

saving

Medium

saving

New

demand

107.9 9.5 14.8 132.1 107.9 9.5 14.8 132.1 2014

111.5 9.8 15.3 136.6 110.0 9.7 15.1 134.8 2015

115.3 10.1 15.8 141.2 112.2 9.9 15.4 137.5 2016

119.2 10.5 16.3 146.0 114.5 10.1 15.7 140.2 2017

123.2 10.8 16.9 150.9 116.8 10.3 16.0 143.0 2018

127.4 11.2 17.5 156.0 119.1 10.5 16.3 145.9 2019

131.7 11.6 18.1 161.3 121.5 10.7 16.7 148.8 2020

136.1 12.0 18.7 166.8 123.9 10.9 17.0 151.8 2021

140.7 12.4 19.3 172.4 126.4 11.1 17.3 154.8 2022

145.5 12.8 20.0 178.2 128.9 11.3 17.7 157.9 2023

150.4 13.2 20.6 184.3 131.5 11.6 18.0 161.1 2024

155.5 13.7 21.3 190.5 134.1 11.8 18.4 164.3 2025

160.8 14.1 22.0 196.9 136.8 12.0 18.8 167.6 2026

166.2 14.6 22.8 203.6 139.6 12.3 19.1 170.9 2027

171.8 15.1 23.6 210.5 142.3 12.5 19.5 174.4 2028

177.6 15.6 24.4 217.6 145.2 12.8 19.9 177.9 2029

183.6 16.1 25.2 224.9 148.1 13.0 20.3 181.4 2030

189.8 16.7 26.0 232.5 151.1 13.3 20.7 185.0 2031

196.2 17.2 26.9 240.4 154.1 13.5 21.1 188.7 2032

202.9 17.8 27.8 248.5 157.2 13.8 21.6 192.5 2033

209.7 18.4 28.8 256.9 160.3 14.1 22.0 196.4 2034

216.8 19.0 29.7 265.6 163.5 14.4 22.4 200.3 2035

14


Appendices

Projections for high water requirements

on 30% adoption rate



Current

case

High

saving

Medium

saving

New

demand

Current

case

High

saving

Medium

saving

New

demand

224.1 19.7 30.7 274.6 166.8 14.7 22.9 204.3 2036

231.7 20.4 31.8 283.9 170.1 14.9 23.3 208.4 2037

239.6 21.0 32.9 293.5 173.5 15.2 23.8 212.6 2038

247.7 21.8 34.0 303.4 177.0 15.5 24.3 216.8 2039

256.0 22.5 35.1 313.6 180.5 15.9 24.8 221.1 2040


Projections for high water requirements on

50% adoption rates



Current

case

High

saving

Medium

saving

New

demand

Current

case

High

saving

Medium

saving

New

demand

77.1 15.8 24.7 117.5 77.1 15.8 24.7 117.5 2014

79.7 16.3 25.5 121.5 78.6 16.1 25.2 119.9 2015

82.4 16.9 26.4 125.6 80.2 16.4 25.7 122.3 2016

85.1 17.5 27.2 129.8 81.8 16.8 26.2 124.7 2017

88.0 18.0 28.2 134.2 83.4 17.1 26.7 127.2 2018

91.0 18.7 29.1 138.8 85.1 17.4 27.2 129.7 2019

94.1 19.3 30.1 143.4 86.8 17.8 27.8 132.3 2020

97.2 19.9 31.1 148.3 88.5 18.1 28.3 135.0 2021

100.5 20.6 32.2 153.3 90.3 18.5 28.9 137.7 2022

103.9 21.3 33.3 158.5 92.1 18.9 29.5 140.4 2023

107.4 22.0 34.4 163.8 93.9 19.3 30.1 143.2 2024

111.1 22.8 35.5 169.4 95.8 19.6 30.7 146.1 2025

114.8 23.5 36.7 175.1 97.7 20.0 31.3 149.0 2026

118.7 24.3 38.0 181.0 99.7 20.4 31.9 152.0 2027

122.7 25.2 39.3 187.1 101.7 20.8 32.5 155.1 2028

126.9 26.0 40.6 193.5 103.7 21.3 33.2 158.2 2029

131.2 26.9 42.0 200.0 105.8 21.7 33.8 161.3 2030

15


Appendices


50% adoption rates



Current

case

High

saving

Medium

saving

New

demand

Current

case

High

saving

Medium

saving

New

demand

135.6 27.8 43.4 206.8 107.9 22.1 34.5 164.5 2031

140.2 28.7 44.9 213.8 110.1 22.6 35.2 167.8 2032

144.9 29.7 46.4 221.0 112.3 23.0 35.9 171.2 2033

149.8 30.7 47.9 228.5 114.5 23.5 36.6 174.6 2034

154.9 31.7 49.6 236.2 116.8 23.9 37.4 178.1 2035

160.1 32.8 51.2 244.2 119.1 24.4 38.1 181.7 2036

165.5 33.9 53.0 252.4 121.5 24.9 38.9 185.3 2037

171.1 35.1 54.8 260.9 123.9 25.4 39.7 189.0 2038

176.9 36.3 56.6 269.8 126.4 25.9 40.5 192.8 2039

182.9 37.5 58.5 278.9 128.9 26.4 41.3 196.6 2040



90% adoption rate



Current

case

High

saving

Medium

saving

New

demand

Current

case

High

saving

Medium

saving

New

demand

15.4 28.4 44.4 88.2 15.4 28.4 44.4 88.2 2014

15.9 29.4 45.9 91.2 15.7 29.0 45.3 90.0 2015

16.5 30.4 47.4 94.3 16.0 29.6 46.2 91.8 2016

17.0 31.4 49.0 97.5 16.4 30.2 47.1 93.6 2017

17.6 32.5 50.7 100.8 16.7 30.8 48.0 95.5 2018

18.2 33.6 52.4 104.2 17.0 31.4 49.0 97.4 2019

18.8 34.7 54.2 107.7 17.4 32.0 50.0 99.4 2020

19.4 35.9 56.0 111.3 17.7 32.7 51.0 101.3 2021

20.1 37.1 57.9 115.1 18.1 33.3 52.0 103.4 2022

20.8 38.3 59.9 119.0 18.4 34.0 53.0 105.4 2023

21.5 39.6 61.9 123.0 18.8 34.7 54.1 107.5 2024

16


Appendices


90% adoption rate



Current

case

High

saving

Medium

saving

New

demand

Current

case

High

saving

Medium

saving

New

demand

22.2 41.0 64.0 127.2 19.2 35.4 55.2 109.7 2025

23.0 42.4 66.1 131.5 19.5 36.1 56.3 111.9 2026

23.7 43.8 68.4 135.9 19.9 36.8 57.4 114.1 2027

24.5 45.3 70.7 140.5 20.3 37.5 58.6 116.4 2028

25.4 46.8 73.1 145.3 20.7 38.3 59.7 118.7 2029

26.2 48.4 75.5 150.2 21.2 39.0 60.9 121.1 2030

27.1 50.0 78.1 155.2 21.6 39.8 62.1 123.5 2031

28.0 51.7 80.7 160.5 22.0 40.6 63.4 126.0 2032

29.0 53.5 83.5 165.9 22.5 41.4 64.7 128.5 2033

30.0 55.3 86.3 171.5 22.9 42.3 66.0 131.1 2034

31.0 57.1 89.2 177.3 23.4 43.1 67.3 133.7 2035

32.0 59.1 92.2 183.3 23.8 44.0 68.6 136.4 2036

33.1 61.1 95.3 189.5 24.3 44.8 70.0 139.1 2037

34.2 63.1 98.6 195.9 24.8 45.7 71.4 141.9 2038

35.4 65.3 101.9 202.5 25.3 46.6 72.8 144.7 2039

36.6 67.5 105.3 209.4 25.8 47.6 74.3 147.6 2040

17


Appendices

Appendix E: Impacts of the suggested solutions

Table E-1: Results of the suggested additional water sources (Units in Mm3/annum)

Year

s

Water

supplie

d to

CoCT

by

WCWS

S

Impact of

climate

change

Actual

trend

in the

previou

s years

Projected

trend of

high water

requiremen

ts

Projected

trend of low

water

requiremen

ts

Aquifer

s

Seawater

desalinatio

n

Reuse

treated

effluent

2003

2004 370 310

2005 370 275

2006 370 295

2007 370 310

2008 399 315

2009 399 325

2010 399 330

2011 399 399 335

2012 399 398.2 330

2013 399 397.4 320

2014 399 396.6 315 315.0 315.0

2015 399 395.8 325.6 321.3

2016 399 395 336.7 327.7

2017 399 394.2 348.0 334.3

2018 399 393.4 359.8 341.0

2019 399 392.6 372.0 347.8

2020 399 391.8 384.5 354.7 391.8

2021 399 391 397.5 361.8 459

2022 399 390.2 411.0 369.1 458.2

2023 399 389.4 424.9 376.5 457.4

2024 399 388.6 439.2 384.0 456.6 456.6

2025 399 387.8 454.1 391.7 455.8 486.8

2026 399 387 469.4 399.5 455 486

2027 399 386.2 485.3 407.5 454.2 485.2 485.2

18


Appendices

2028 399 385.4 501.7 415.6 453.4 644.4 484.4

2029 399 384.6 518.6 423.9 452.6 643.6 483.6

2030 399 383.8 536.2 432.4 451.8 642.8 482.8

2031 399 383 554.3 441.1 451 642 482

2032 399 382.2 573.0 449.9 450.2 641.2 481.2

2033 399 381.4 592.4 458.9 449.4 640.4 480.4

2034 399 380.6 612.4 468.1 448.6 639.6 479.6

2035 399 379.8 633.1 477.4 447.8 638.8 478.8

2036 399 379 654.5 487.0 447 638 478

2037 399 378.2 676.6 496.7 446.2 637.2 477.2

2038 399 377.4 699.5 506.7 445.4 636.4 476.4

2039 399 376.6 723.1 516.8 444.6 635.6 475.6

2040 399 375.8 747.6 527.1 443.8 634.8 474.8

Table E-2: Combined results of water supply increase and demand reduction on LWR

projections (Units in Mm3/annum)

Yea

rs

Water

suppli

ed to

CoCT

by

WCW

SS

Impa

ct of

clim

ate

chan

ge

Actua

l

trend

in the

previ

ous

years

Project

ed

trend

of low

water

require

nts

Impac

t after

30%

WED

adopti

on

rate

Impac

t after

50%

adopti

on

rate

Impac

t after

90%

WED

adopti

on

rate

Final

result

s

Aquif

ers

Seawate

r

desalina

tion

Reus

e

treat

ed

efflue

nt

200

3

200

4

370 310

200

5

370 275

200

6

370 295

200

7

370 310

19


Appendices

Yea

rs

Water

suppli

ed to

CoCT

by

WCW

SS

Impa

ct of

clim

ate

chan

ge

Actua

l

trend

in the

previ

ous

years

Project

ed

trend

of low

water

require

nts

Impac

t after

30%

WED

adopti

on

rate

Impac

t after

50%

adopti

on

rate

Impac

t after

90%

WED

adopti

on

rate

Final

result

s

Aquif

ers

Seawate

r

desalina

tion

Reus

e

treat

ed

efflue

nt

200

8

399 315

200

9

399 325

201

0

399 330

201

1

399 399 335

201

2

399 398.2 330

201

3

399 397.4 320

201

4

399 396.6 315 315.0 315

201

5

399 395.8 321.3 321.3

201

6

399 395 327.7 327.72

6

201

7

399 394.2 334.3 334.3 334.3

201

8

399 393.4 341.0 318.3 318.27

57

201

9

399 392.6 347.8 324.6 324.6 324.6

202

0

399 391.8 354.7 331.1 315.4 315.39

59

202

1

399 391 361.8 337.8 321.7 321.70

39

20


Appendices

Yea

rs

Water

suppli

ed to

CoCT

by

WCW

SS

Impa

ct of

clim

ate

chan

ge

Actua

l

trend

in the

previ

ous

years

Project

ed

trend

of low

water

require

nts

Impac

t after

30%

WED

adopti

on

rate

Impac

t after

50%

adopti

on

rate

Impac

t after

90%

WED

adopti

on

rate

Final

result

s

Aquif

ers

Seawate

r

desalina

tion

Reus

e

treat

ed

efflue

nt

202

2

399 390.2 369.1 344.5 328.1 328.1 328.1

202

3

399 389.4 376.5 351.4 334.7 301.3 301.29

79

202

4

399 388.6 384.0 358.4 341.4 307.3 307.3

202

5

399 387.8 391.7 365.6 348.2 313.5 302.8

202

6

399 387 399.5 372.9 355.2 319.7 308.9

202

7

399 386.2 407.5 380.4 362.3 326.1 315.0 386.2

202

8

399 385.4 415.6 388.0 369.5 332.7 321.3 453.4

202

9

399 384.6 423.9 395.7 376.9 339.3 327.8 452.6

203

0

399 383.8 432.4 403.7 384.5 346.1 334.3 451.8

203

1

399 383 441.1 411.7 392.2 353.0 341.0 451 451

203

2

399 382.2 449.9 420.0 400.0 360.1 347.8 450.2 481.2

203

3

399 381.4 458.9 428.4 408.0 367.3 354.8 449.4 480.4

203

4

399 380.6 468.1 436.9 416.2 374.6 361.9 448.6 479.6 479.6

203

5

399 379.8 477.4 445.7 424.5 382.1 369.1 447.8 638.8 478.8

21


Appendices

203

6

399 379 487.0 454.6 433.0 389.8 376.5 447 638 478

203

7

399 378.2 496.7 463.7 441.6 397.6 384.0 446.2 637.2 477.2

203

8

399 377.4 506.7 472.9 450.5 405.5 391.7 445.4 636.4 476.4

203

9

399 376.6 516.8 482.4 459.5 413.6 399.6 444.6 635.6 475.6

204

0

399 375.8 527.1 492.0 468.7 421.9 407.5 443.8 634.8 474.8

Table E-3: Combined results of water supply increase and demand reduction on HWR

projections (Units in Mm3/annum)

Yea

rs

Water

suppli

ed to

CoCT

by

WCW

SS

Imp

act

of

clim

ate

chan

ge

Actua

l

trend

in the

previ

ous

years

Projecte

d trend

of high

water

requirem

ents

30%

WED

adopt

ion

50%

WED

adopt

ion

90%

WED

adopt

ion

Final

result

s

Aquif

ers

Seawate

r

desalina

tion

Reus

e

treat

ed

efflu

ent

200

3

200

4

370 310

200

5

370 275

200

6

370 295

200

7

370 310

200

8

399 315

200

9

399 325

201

0

399 330

201

1

399 399 335

22


Appendices

Yea

rs

Water

suppli

ed to

CoCT

by

WCW

SS

Imp

act

of

clim

ate

chan

ge

Actua

l

trend

in the

previ

ous

years

Projecte

d trend

of high

water

requirem

ents

30%

WED

adopt

ion

50%

WED

adopt

ion

90%

WED

adopt

ion

Final

result

s

Aquif

ers

Seawate

r

desalina

tion

Reus

e

treat

ed

efflu

ent

201

2

399 398.

2

330

201

3

399 397.

4

320

201

4

399 396.

6

315 315.0 315

201

5

399 395.

8

325.6 325.6

47

201

6

399 395 336.7 336.6

539

201

7

399 394.

2

348.0 348.0 348

201

8

399 393.

4

359.8 335.9 335.8

527

201

9

399 392.

6

372.0 347.2 347.2 347.2

202

0

399 391.

8

384.5 358.9 341.9 341.8

804

202

1

399 391 397.5 371.1 353.4 353.4

36

202

2

399 390.

2

411.0 383.6 365.4 365.4 365.4

202

3

399 389.

4

424.9 396.6 377.7 340.0 340.0

348

202

4

399 388.

6

439.2 410.0 390.5 351.5 351.5

202

5

399 387.

8

454.1 423.8 403.7 363.4 351.1

202

6

399 387 469.4 438.2 417.3 375.7 362.9

202

7

399 386.

2

485.3 453.0 431.4 388.4 375.2 386.2

202

8

399 385.

4

501.7 468.3 446.0 401.5 387.9 453.4

202

9

399 384.

6

518.6 484.1 461.1 415.1 401.0 452.6

203

0

399 383.

8

536.2 500.5 476.7 429.1 414.5 451.8

23


Appendices

Yea

rs

Water

suppli

ed to

CoCT

by

WCW

SS

Imp

act

of

clim

ate

chan

ge

Actua

l

trend

in the

previ

ous

years

Projecte

d trend

of high

water

requirem

ents

30%

WED

adopt

ion

50%

WED

adopt

ion

90%

WED

adopt

ion

Final

result

s

Aquif

ers

Seawate

r

desalina

tion

Reus

e

treat

ed

efflu

ent

203

1

399 383 554.3 517.4 492.8 443.6 428.5 451 451

203

2

399 382.

2

573.0 534.9 509.5 458.6 443.0 450.2 481.2

203

3

399 381.

4

592.4 553.0 526.7 474.1 458.0 449.4 480.4

203

4

399 380.

6

612.4 571.7 544.5 490.1 473.5 448.6 479.6 479.6

203

5

399 379.

8

633.1 591.0 562.9 506.7 489.5 447.8 638.8 478.8

203

6

399 379 654.5 611.0 581.9 523.8 506.0 447 638 478

203

7

399 378.

2

676.6 631.6 601.6 541.5 523.1 446.2 637.2 477.2

203

8

399 377.

4

699.5 652.9 621.9 559.8 540.8 445.4 636.4 476.4

203

9

399 376.

6

723.1 675.0 642.9 578.8 559.1 444.6 635.6 475.6

204

0

399 375.

8

747.6 697.8 664.7 598.3 578.0 443.8 634.8 474.8

24


Appendices

Appendix F: The CoCT’s plans to increase future

supply

Table F-1: Future projects to increase water supply (Adapted from Reconciliation Strategy,

2008)

Options for Cape Town’s future projects Descriptions of the projects

Raising Lower Steenbras Dam

24m raising of the Lower Steenbras Dam to the same full

supply level (FSL) as the Upper Steenbras Dam. The

scheme includes existing and potential transfers from the

Palmiet River and runoff from within Steenbras Dam's

catchment.

Construction of new Dam (Upper Campanula

dam)

Construction of a 50Mm3 dam on the lower Palmiet River,

and a pipeline and canal to the existing Kogelberg Dam.

Water transferred to a raised Lower Steenbras Dam via the

existing Palmiet Pumped Storage Scheme.

Lourens River Diversion

The scheme involves the construction of a weir on the

Lourens River diverting winter water directly into the

Steenbras – Faure pipeline.

Eerste River Diversion

The scheme involves the construction of 4m high (35000m3

capacity) weir on the Eerste River, with pumping into a new

off-channel balancing dam and on to the Faure WTW. A

bypass pipeline would be required from Stellenbosch due to

water quality concerns.

Voelvlei Augmentation

The scheme requires a 1 m high weir and intake on the Berg

River near Spes Bona. Winter water (3m3/s) would be

pumped over 5km to the Voëlvlei WTW. Treatment would

be for direct delivery to Cape Town or alternatively, pre-

treatment for storing water in Voëlvlei Dam. The scheme

would optimise spare capacity in the existing WTW and in

the pipeline to Cape Town (total 20Mm3/a). Balance to

supply other users reliant on Voëlvlei Dam.

Construction of new dam at Misverstand

This option takes the Berg River Project into account. Phase

2 involves a 9m raising of Voëlvlei Dam. Phase 3 involves

a 7.5m high (4Mm3 capacity) weir on the Berg River and a

rising main to the Voëlvlei Dam, with a diversion capacity

of 20 m3/s. A 1.5m diameter steel pipeline to Cape Town

would also be required.

Construction of Twenty-four Rivers Dams

This scheme involves the construction of a 21m high

rockfill dam at the existing diversion weir site on the

Twenty-four Rivers. The potential dam would act as a

25


Appendices

balancing dam to improve the efficiency of diversions into

Voëlvlei Dam.

Construction of Waterval River Dam

The dam would be located in the catchment adjacent to

Voëlvlei Dam. A 14m high rockfill dam (12Mm3 capacity)

would feed water via a tunnel into the Voëlvlei Dam.

Michell’s Pass Diversion

This option entails the construction of a 10m high weir on

the Dwars River diverting winter water via a 9km canal into

the Klein Berg River, and then to the Voëlvlei Dam.

Diversion capacities of 4.8 and 12m3/s have been

investigated.

Raising Theewaterskloof Dam

This option only has a benefit if developed in conjunction

with Brandvlei to theewaterskloof transfer scheme; There is

little yield benefit from runoff from its own catchment and

high evaporation is an issue.

Construction of Lower Wit River Dam

This scheme entails the construction of a 28m high (24Mm3

capacity) rockfill dam at the bottom of Bain's Kloof on the

Lower Wit River. Winter water (1.2m3/s) would be pumped

across the catchment divide, then gravity fed to the Klein

Berg River and into the Voëlvlei Dam.

Wemmershoek Dam and pipeline

This option would connect the Wemmershoek Dam to the

Berg River Dam. Surplus water from Wemmershoek Dam

catchment could be transferred to the Berg River Dam,

either by flow reversal in the Wemmershoek pipeline or via

a new pipeline.

Upper Molenaars Diversion

Involves the construction of a pumping sump in the

Molenaars River. Winter flows would be pumped at 5m3/s

through the Huguenot Tunnel (existing 1.2m diametr pipe),

before being gravity fed to either the Berg River Dam or the

Wemmershoek Dam via 26km of new pipeline.

Brandvlei to Theewaterskloof transfer

This option entails the augmentation of the Greater

Brandvlei Dam by increased Papenkuils abstraction with

direct pumping into the Greater Brandvlei Dam. Water

would then be transferred by pipeline, canal and tunnel to

the Theewaterskloof Dam.

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