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Vision 2030

The resilience of water supply and

sanitation in the face of climate change

Technology fact sheets

Authors:

Dr Katrina Charles, Robens Centre for Public and Environmental Health, University of Surrey

Dr Kathy Pond, Robens Centre for Public and Environmental Health, University of Surrey

Dr Steve Pedley, Robens Centre for Public and Environmental Health, University of Surrey

Contributors:

The authors would like to thank the following individuals who participated in a working session to

define climate risks and technology vulnerabilities and adaptations:

Mr Chee-Keong Chew, Water, Sanitation, Hygiene and Health, World Health Organization

Dr Barbara Evans, Water and Environment, University of Leeds

Professor Barry Lloyd, Centre for Environmental Health Engineering, University of Surrey

Mr Brian Reed, Water, Engineering and Development Centre, Loughborough University

Ms Beth Scott, Policy and Research Division, Department for International Development

Professor Mike Smith, Water, Engineering and Development Centre, Loughborough University

Dr David Sutherland, Principal Consultant, Atkins

Dr Richard Taylor, Department of Geography, University College London

Disclaimer

The fact sheets were prepared in good faith. The named authors alone are responsible for the views

expressed in this publication. Neither the World Health Organization and University of Surrey, UK,

nor their employees, contractors or subcontractors, make any warranty, express or implied, or

assume any legal liability or responsibility for its accuracy, completeness, or any party’s use of its

contents.

The fact sheets are not edited by the World Health Organization to conform to the full requirements

of WHO style. The published material is being distributed without warranty of any kind, either

expressed or implied. The responsibility for the interpretation and use of the material lies with the

reader. In no event shall the World Health Organization be liable for damages arising from its use.

Introduction

The Technology projection study (included in this CD-ROM) discusses a number of themes related

to climate change, and in particular describes the consequential changes in rainfall patterns, and the

observed and perceived impact of these changes on drinking-water supply and sanitation facilities.

The evidence gathered from the literature, and from the opinions and experiences of experts

working in the field, demonstrates the vulnerability of drinking-water supply and sanitation

facilities, at all levels of sophistication, to the vagaries of the present climate. These observations

suggest that without intervention, the vulnerability of these facilities to climate-induced damage

will increase in the future as climate conditions become more extreme. This assumption is

supported by the opinions of many of those working in the water and sanitation sector.

The evidence gathered in preparing that report also showed that there are interventions that can be

made to reduce the vulnerability of drinking-water supply and sanitation facilities to climate

change. Several examples of successful adaptation were noted. Based on the positive results of

those interventions and the opinions of water and sanitation professionals, we have compiled a

series of fact sheets containing guidance about the kind of interventions that may be considered

suitable for increasing the resilience of drinking-water supply and sanitation facilities to the

consequences of several climate-change scenarios. These notes should not be considered a complete

authoritative guide to the interventions that can be made to protect these facilities from climate

change. The impacts of changing patterns of rainfall are many and varied, and will be conditional

on the local environment. Similar scenarios, therefore, will have different consequences depending

on where they occur. These guidance notes provide a first attempt at presenting a framework for

adaptation in the water supply and sanitation sector and, as such, they are intended to raise

awareness of the potential problems that will be faced in the short to medium term in the water and

sanitation sector. Their contents are not fixed but will change and grow over time as new

knowledge and experience are added to them. Most of all, however, the guidance notes are intended

to promote debate in the water and sanitation sector.

The intended users of these guidance notes are water supply and sanitation professionals, water

resource managers, public health professionals, communities managing their own water supplies,

and nongovernmental organizations working in the water supply and sanitation sector.

Four climate scenarios are addressed in these vulnerability and adaptation guidance notes:

• increase in precipitation, with increase in rainfall intensity;

• increase in precipitation, with no increase in rainfall intensity;

• decrease in precipitation, with increase in rainfall intensity;

• decrease in precipitation, with no increase in rainfall intensity.

The fact sheets are divided up by key issues for water supply and sanitation facilities as a result of

these four climate scenarios. The relevant key issues for each scenario are indicated in Table 1.

The adaptations have been divided into four categories:

• capital expenditure, which includes long-term adaptations that will not necessarily be

suitable for immediate implementation;

• operational expenditure, which includes adaptations that can be made to existing systems;

• monitoring, which includes programmes that can be implemented immediately to support

planning decisions, or implemented in the long term to support continuing decisions;

• Socioeconomic tools such as community education, training and public awareness that can

support short-term and long-term adaptations.

Table 1

Summary of problems relating to climate change for four different scenarios

Scenario Key issues

Increase in

precipitation,

increase in

rainfall

intensity

Increase in

precipitation,

no increase in

rainfall

intensity

Decrease in

precipitation,

increase in

rainfall

intensity

Decrease in

precipitation,

no increase in

rainfall

intensity

Increased risk of flooding � � �

Increase in groundwater

recharge, with a rise in groundwater level, increases in

interflow and more saturated

soils

� �

More extreme rainfall events � �

Increased run-off with more

erosion

� �

Water availability decreases

including less surface flow, drop

in surface water levels, and

decreased groundwater levels

� �

In all cases we refer the reader to the Water Safety Plan approach as a means of consistently

ensuring the safety of a drinking-water supply. Model water safety plans for the water facilities

referred to below are provided in

http://www.who.int/water_sanitation_health/dwq/wsp170805AppB.pdf.

The water supply and sanitation facilities discussed in these fact sheets are those defined as

“improved” by the WHO/UNICEF Joint Monitoring Programme on Water Supply and Sanitation

(see Table 2). Levels of coverage are discussed in Chapter 4 of the Technology projection study,

based on data from the WHO/UNICEF Joint Monitoring Programme.

The fact sheets provide guidance with regard to vulnerability and adaptation of water supply and

sanitation facilities to the effects of climate change. They deal with the following key themes:

Water supply

− Flooding increases

− Groundwater recharge increases

− Increase in extreme rainfall events

− Run-off increases

− Water availability decreases

Sanitation

− Flooding increases; increase in extreme rainfall events

− Groundwater tables rising

− Water availability decreases.

Table 2

Definitions of improved water supply and sanitation facilities

Water supply or sanitation

facility

Notes or definition

Utility-managed piped water

supplies

May have either a surface water or groundwater source, and include

infrastructure such as a reservoir and a treatment plant, with treated

water delivered to users via a piped network.

Community-managed drinking-

water systems

These may be with piped or non-piped distribution. The definition of a

community drinking-water system will vary. It may be based on

population size or the type of supply; or based on the approaches to

administration and management. Drinking-water systems in periurban

areas in developing countries – the communities surrounding major

towns and cities – may also have the characteristics of community

systems.

Public standpipes Standpipes deliver water supplied by a utility or community managed

supply, and hence have the same vulnerabilities as one of those systems.

However, with public standpipes, the water is not delivered to the

consumers, but to a tap or standpipe for which there is public access.

Protected wells Includes boreholes and dug wells.

Protected springs A protected spring is one in which the eye of the spring (where the water emerges from the ground) has a protective wall or box around it.

The area behind the box is backfilled with stones to filter the

groundwater.

Rainwater collection Collection of rainwater from roofs: rainwater is collected in guttering

placed around the eaves of the building.

Sewers Sewer systems collect all household wastewater, as well as industrial

and commercial wastewater, and transport it via a network of sewerage pipes to a central treatment or disposal site. Combined sewer systems

are included in the definition of sewers.

Septic tanks Septic tanks collect all household wastewater, and should collect only

wastewater, not storm water.

Improved pit latrines Includes pour-flush latrine, and simple (or double) pit or ventilated

improved pit latrine, allowing for acceptable local technologies.

Composting or dry latrines Composting or dry latrines are constructed with the collection chamber

for faeces (and urine) above ground. The position of the collection

chamber facilitates drying of the contents and easy access for its

removal.

Key issue: Flooding increases Utility-managed piped water supplies

Adaptation methods Vulnerability Impacts

Capital expenditure Operational expenditure Monitoring Socioeconomic tools

Increased flooding

reduces the availability

of safe water resources.

Flooding events increase

the level of chemical and

microbiological

contamination in water

sources, increasing the

risk to public health.

Increased suspended

sediment load carried by flood waters exceeds the

treatment capacity of

water treatment facilities.

Develop, implement and

update water safety plans.

Design flood storage areas

on rivers to mitigate the

impacts of floods. This may

include implementing land

management activities to

increase infiltration of water and reduce severity of

floods, e.g. terracing,

adequate urban drainage, reforestation, retention

basins.

Adopt higher design

standards for infrastructure

to take higher and more

frequent floods into

consideration, particularly in

terms of return periods for significant events.

Best management practices (grass swales, permeable

surfaces, balancing ponds).

Seasonal forecasting.

Flood forecasting.

Hydrological monitoring

stations.

Rain gauging.

Earth observation data.

Enhanced inspection of

infrastructure.

Raise awareness among

the public of the risk of

contamination during

floods and the reduction

in drinking-water

availability.

Dissemination of public

health advisory notices with advice about dealing

with the issues.

Possible mechanisms

include posting leaflets,

door-to-door visits, and

radio and television

announcements.

Fluctuating surface

water levels may cause

problems for

infrastructure

Water intakes may be

left exposed as water

levels fall.



Design water intake to

Switch to groundwater

sources when available.

Repair damage as


stations. Rain gauging.



operational managers of

the need for enhanced

inspection procedures.



Highly turbulent water

flows in rivers after

heavy rain may damage

intakes.

accommodate varying water

levels (for example floating

booms). River intakes

strengthened to withstand

more turbulent flows.

Develop groundwater

sources where feasible.

necessary.

Plan for emergency water

supplies.


infrastructure

Communicate the

justification for enhanced

inspection as a result of

climate change.

Floods may overtop

reservoir causing

structural damage

Catastrophic failure of

dams, leading to reduced

storage capacity and

potentially damaging

releases of water.

Design overflows for source

reservoirs to prevent failure

Maintain spillways and

channels in good order.

Early warning system

installed.

Disseminate early

warnings.

Update and disseminate

evacuation procedures.

Increase frequency with

which emergency

procedures are practised.

Flooding of treatment system

Floods may lead to structural damage of the

treatment works, or to

the failure of pumping stations. Water supplies

fail.

Develop, implement and update water safety plans.

Site water treatment works and other major

infrastructure away from

flood zones, or build

appropriate flood defences.

Protect electrical

installations.

Smaller more localized treatment systems may help

to spread risk of widespread

water shortages.

Plan after-flooding response to assess and

address infrastructure

damage.

Take treatment unit offline

and apply corrective action.

Planned emergency

response. Increase

chlorination. Plan for

emergency supplies.

Intensify monitoring of water quality after event

and before going back

on line.

Manage communication of early warning of event

to the public.

Develop communication

procedures for notifying

the public when the water

is safe. Possible

mechanisms include

posting leaflets, door-to-

door visits, and radio and

television

announcements.


water engineers of risks



from water quality

changes during flooding

and how water treatment

can be adapted to manage

the risks.

Groundwater quality

deterioration during floods

Floodwaters contaminate

shallow and deep groundwater sources

through damaged or

disused boreholes.

Shallow groundwater

may also be affected by

infiltration of flood

water through soil

layers.



Improve source protection.

Introduce chlorination where

not previously applied.

Relocate groundwater

source.

Impose well head

protection areas and well head inspection

procedures.

Increase chlorination of the

water after flood.

Intensify water quality

monitoring after flood.


water engineers of risks from water quality


and how water treatment

can be adapted to manage

the risks.

Manage communication

of early warning of event

to the public.


procedures for when

water is safe. Possible mechanisms include


door visits, and radio and

television

announcements.

Surface water quality

deterioration during

floods.

Floodwater carries

increased sediment load

that may exceed the

treatment capacity of the

water treatment works.

Run-off water from

upstream may carry



Adapt water treatment for

flood conditions depending on water source and

contamination.

Select appropriate water

treatment stages to suit

water quality.

Dig out buried intakes after flood waters recede.

Design and implement a

monitoring programme

of flooding in water

sources.

Monitor silt build-up in

reservoirs.



from water quality


and how water treatment can be adapted to manage

the risks.



higher concentrations of

chemical and microbial

contaminants.

Introduce additional, more

robust barriers and treatment

stages.

Relocate abstraction points.

Monitor raw water

quality.


of early warning of event

to the public.


procedures for when water is safe. Possible

mechanisms include

posting leaflets, door-to-door visits, and radio and

television

announcements.

Entry of contaminated

flood water into water

supply pipes.

Localized or widespread

contamination of the

water distribution

system.



Where possible, aim to site

pipes in area of low risk of flooding.

In areas where flooding is likely, aim to keep water and

sewage pipes separate in

case of cross contamination

through fractures.

Relocate water pipes away

from open sewers and

drainage channels.

Implement pipe

maintenance programme to

reduce leakage and the

potential for ingress.

Implement pipe

maintenance programme to

reduce leaks from sewers, particularly where located

close to water pipes and

where cross connection is

possible. Include cut-off

walls in high-risk areas.

Implement rehabilitation

programmes to improve

hydrostatic pressure.

Flush out flooded pipe

network after waters have receded to remove

sediments. Shock



for flooding of the pipe

network. This might

include monitoring of water pressure in pipes,

water quality

monitoring, or a reporting mechanism for

when areas above pipes

are flooded.

Review risks and need

for refurbishment or

replacement.

Raise awareness amongst

the public of

contamination issues

during floods and

reduction in drinking-water availability. This

may be done by posting

leaflets, door-to-door visits; radio and TV

announcements to inform

people to boil water.



chlorinate the system and

introduce increased

chlorination until risk of

contamination has been

reduced.


water at service reservoir.


contamination of the water distribution

system.



Re-line reservoirs.

Re-point concrete reservoirs.

Replace or repair damaged

access points to the service

reservoir.

Clear drainage channels.

Take tanks offline for

repairs.

Flush tank and distribution

before re-commissioning.

Repair leaks, drains and

valve box. Repair valve if

showing signs of wear

Validation by water

quality monitoring at times of major works.

Regular inspection.

Periodic integrity testing.

Tracer tests.


the public of contamination issues

during floods and

reduction in drinking-

water availability. This


leaflets, door-to-door

visits, and radio and

television announcements

to inform people to boil

water.

Contamination of drinking-water in supply

affecting large

populations.

Major public health risk. Develop, implement and update water safety plans.

Decentralize and diversify water systems to mitigate

the number of people

affected.

Develop back-up sources,

such as linkages to other

sources or emergency tank

supplies, to mitigate risk.

Zoning of water supplies for monitoring and

management of distribution

system.

Implement leak detection

and repair procedures.

Intensification of water quality monitoring above

minimum level specified

in WHO guidelines.

Raise awareness among the public of

contamination issues

during floods and reduction in drinking-

water availability. This


leaflets, door-to-door

visits, and radio and

television

announcements.

Establish communication procedures with the

relevant public health

departments.



May also require the

issue of warnings to boil

water.

Enhance and practice emergency response

procedures.

Flooding causes damage

to bridges that support

trunk mains or

distribution pipes over

rivers.


disruption to water

supplies.



Review relative risks and the

cost-benefits of laying the

trunk main under the river or

supporting from bridge over

the river. Select most cost-

beneficial option.

Install multiple crossings for

distribution pipes.

Install isolation valves at

both sides of crossing.

Carry out regular

inspection and

vulnerability assessment

of structures.

Develop monitoring,

management and

communication

procedures with the

bridge owners, if

different from water

supply provider.

Community-managed piped water supplies



Increased flooding

reduces the availability

of safe water resources.

Flooding events increase

the level of chemical and

microbiological

contamination in water

sources, increasing the risk to public health.



Adopt higher design

standards for infrastructure to take

Seasonal forecasting.

Flood forecasting.

Establish centralized support unit to provide


stations.

Enhanced inspection of infrastructure.


the community of the

risk of contamination

during floods and

reduction in drinking-water availability.



Increased suspended

sediment loads carried

by flood waters may

exceed the treatment

capacity of any small-scale water treatment

system that has been

added to the supply.

higher and more frequent

floods into consideration,

particularly in terms of

return periods for

significant events.

Where possible,

implement land

management activities to increase infiltration of

water and reduce severity

of floods, e.g. terracing,

reforestation.

technical and

administrative assistance

in the event of flooding


health messages with

advice about dealing

with the issues,

including household treatment and boil water

notices where

appropriate. This may be done by posting leaflets,

door-to-door visits, radio

and television

announcements, and by

posting notices in

prominent places in the

community.

Fluctuating surface water levels may cause

problems for

infrastructure.

Water intakes may be left exposed as water

levels fall.

Highly turbulent water

flows in rivers after

heavy rain may damage

intakes.


Strengthen river intakes to withstand more turbulent

flows.

Develop groundwater

sources where feasible.


technical and

administrative assistance in the event of flooding.

Switch to alternative

sources when available.

Repair damage as

necessary.

Plan for emergency water supplies.

Hydrological monitoring stations.

Enhanced inspection of infrastructure

Raise awareness among community members of

the need for enhanced

inspection procedures.

Communicate the

justification for

enhanced inspection as a

result of climate change.

Floods may overtop

reservoir causing

structural damage.


the dam, leading to

reduced storage capacity

Design overflows for

source reservoirs to

prevent failure.

Maintain spillways and

channels in good order.

Evaluate need for early

warning system.

Disseminate early

warnings.



and potentially

damaging releases of

water.

Evaluate the need for

evacuation procedures.

Increase frequency with

which emergency

procedures are practised if appropriate.

Flooding of water

treatment system.

Distribution of

contaminated water

through the distribution

system.

Water supplies fail.

Structural damage to the

treatment system.



Site the water treatment

works and other major

infrastructure away from

flood zones, or build

appropriate flood

defences.

Protect electrical

installations, e.g. with

walled treatment plant or sandbag defences.

Establish centralized

support unit to provide

technical and

administrative assistance

in the event of flooding.

Plan after-flooding

response to assess and


damage. Take treatment unit

offline and apply

corrective action.

Planned emergency

response. Increase

chlorination. Plan for

emergency supplies.

Sanitary inspection.

Increase monitoring of

water quality after event

and before going back

on line, possibly using

external support systems.


of early warning of

event.


procedures for when

water is safe.

Raise awareness of risks

from water quality changes during flooding

Raise awareness about risks from infrastructure

damage after flooding

and how to assess and

address them.

Raise awareness of the

need for household water

treatment.

Groundwater quality

deterioration during floods.

Floodwaters contaminate

shallow and deep groundwater sources

through damaged or

disused boreholes.



Improve source

protection.

Impose well head

protection areas and well head inspection.


Intensify water quality

monitoring after flood.


procedures for when water is safe.



Shallow groundwater

may also be affected by

infiltration of floodwater

through soil layers.

Risk to public health from consuming the

water.

Relocate groundwater

source where possible.

Shock chlorination after

flood.

Raise awareness about

risks from water quality


and the need for

household water

treatment. Possible mechanisms include


door visits, radio and television

announcements, and

positing notices in


community

Surface water quality

deterioration during

floods.

Floodwater carries

increase sediment load

that may exceed the treatment capacity of any

small-scale water

treatment system that is part of the supply

system.

Run off water from

upstream may carry

higher concentrations of

chemical and microbial

contaminants.

Risk to public health

from consuming the

water.



Adapt water treatment for

flood conditions

depending on water source and contamination.

Introduce additional more

robust barriers and

treatment stages.

Relocate abstraction

points, where possible.

Select appropriate water

treatment stages to suit

water quality.

Dig out buried intakes

after the flood waters recede.


Simple monitoring of raw water quality, e.g.

turbidity.


procedures for when

water is safe.


risks from water quality changes during flooding

and the need for

household water

treatment. Possible

mechanisms include


door visits, radio and

television

announcements, and posting notices in


community.



Issue boil water notices

where appropriate.


flood water into water

supply pipes.

Widespread


water supply system.

Risk to public health from consuming the

water.



Aim to site pipes in area

of low risk of flooding.

Relocate water pipes away

from open sewers and

drainage channels.

Introduce a pipe

maintenance programme

to reduce leakage and

potential for ingress,

possibly with the aid of a central support system.

Rehabilitation to

improve hydrostatic

pressure.

Flush out flooded pipe

network after waters

have receded to remove

sediments.

Shock chlorination.


Develop and implement

reporting mechanism

when areas above pipes are flooded.

Review risks and need

for refurbishment or

replacement.




and the need for

household water treatment. This may be

done by posting leaflets,

door-to-door visits, radio

and television

announcements, and

posting notices in


community.

Issue boil water notices where appropriate.

Develop communication procedures for when

water is safe

Contamination of

drinking-water in supply

affecting whole

community.

Severe risk to public

health from consuming

the water.



Develop back-up sources,

such as linkages to other

water sources or

community water supply

systems.

Develop emergency back-

up supplies.

Regular programme of

leak detection and repair.

Sanitary inspection. Raise awareness about



and the need for

household water

treatment

Issue boil water notices where appropriate.




procedures for when

water is safe

This may be done by

posting leaflets, door-to-door visits, radio and

television

announcements, and posting notices in


community.

Enhance and practise

emergency response

procedures.

Flooding causes damage to bridges that support

mains or distribution

pipes over rivers.

Localized or widespread disruption to water

supplies.


Review risks and benefits of burying main under

river or supporting from

bridge over the river.

Select least risk option.

Install isolation valves at

both sides of crossing.

Carry out regular inspection and

vulnerability assessment

of structures.

Develop monitoring, management and

communication

procedures with the bridge owners, if not

owned by the

community.

Public standpipes



See also utility- and community-managed piped water supplies

Standpipes inundated

with contaminated

floodwater.

Standpipes become

inaccessible or are

damaged by the floodwater.

Quality of the water at the standpipe

deteriorates and there is

potential for more

widespread


distribution system.


update water safety

plans.

Place on elevated

platform to allow access during floods.

Construct standpipes

from durable materials to

reduce damage during

floods.

Review the risks and

benefits of removing the standpipe if it is located

in an area at high risk of

flooding.

Adopt a standpipe

maintenance programme

to reduce potential for ingress (e.g. chambers

are sealed).

Develop response plan

after flooding to assess

damage to standpipes

and to inform future

improvement.

Flush out pipes and

clean standpipes after

floods.

Sanitary inspection of

standpipe.

Increase water quality

monitoring after floods

have receded.



changes during flooding and the need for

household water

treatment.


where appropriate.


procedures for when

water is safe.

This may be done by posting leaflets, door-to-

door visits, radio and

television

announcements, and

posting notices in


community.

Protected wells (boreholes and dug wells)



Increased contamination

of groundwater and lateral flow in soil.

Floodwaters introduce

contamination into the groundwater by

Site well away from

latrines and other sources of groundwater

Repair rendering of well

wall when necessary.


Monitor the response of

Prevent latrines being

constructed nearby.



infiltration though the

soil, by damaged or

disused bore holes or

dug wells. Lateral flow

increases, transporting

contaminants below the surface.

Significant public health risks from consuming

the water.

pollution. groundwater levels and

quality to flooding, to

identify vulnerability.




and the need for

household water

treatment.


where appropriate.


procedures for when

water is safe.

This may be done by

adding warning labels to

contaminated wells and

boreholes and removing the notices when the

water is safe.

In areas where there is a

high density of boreholes

and dug wells, consider

developing an

association of well

owners and stakeholders

to manage and monitor wells and provide

guidance to users.

Raise awareness of well

use in emergency

situations.



Well is inundated.

Widespread


aquifer, causing long-

term problems with the

quality of water in the

well.

Significant public health

risks from consuming the water.

Build bunds (banks,

dykes or levees) to divert

flow, or raise the well

head.

Site on embankments.

For deep wells, ensure

the casing extends below the level of shallow

aquifers.

Extend lining above

ground.

Convert dug wells to

hand pumped tubewells

with sanitary completion.

Improve well lining to

prevent ingress of water

from soil and shallow

groundwater, where

appropriate.

Implement land

management activities to reduce severity of


adequate drainage, reforestation, retention

basins.

Repair and clear ditches.

Increase size of ditch.

Repair plinth.

Shock chlorinate well

water after the floods

have subsided.

Provision of alternative

water sources during

inundation or household

treatment.


Increase water quality

monitoring.

Monitor conductivity if in coastal or estuarine

areas.



changes during and after

flooding, and the need

for household water

treatment.


where appropriate.


procedures for when

water is safe.

This may be done by



boreholes and removing the notices when the

water is safe.

In areas where there is a

high density of boreholes


developing an

association of well


to manage and monitor wells and provide

guidance to users.

Raise awareness of well

use in emergency

situations.



Prepare flood risk map

and update as necessary.

Protected springs




surface water at the

spring.

Erosion around the

spring box, damaging

protection.

Quality of water from

the spring deteriorates.

Water quality changes

may be rapid but short-

term if contamination

enters at the spring.

Significant public health risks from consuming

the water.

Ensure spring water

collection and storage

infrastructure are

properly designed,

protected and maintained

to prevent entry of

contaminated water, and

are constructed from durable materials.

Build bunds (banks, dykes or levees) and cut-

off drains to divert flow

away from collection

area.

Regularly check the

infrastructure and repair

if necessary.

Maintain surface water

diversion ditch above

and around spring.



users about risks from

water quality changes

during and after flooding

and the need for

household water

treatment.

Advise community to

avoid using

contaminated springs for drinking during and after

floods, until quality has

been verified.


where appropriate.


procedures for when water is safe.

Groundwater quality deteriorates.

Quality of the water from the spring

deteriorates. Water

Investigate alternative sources if appropriate

and possible.

Properly seal abandoned wells to protect

groundwater quality.

Water quality monitoring after a flood

to verify that water

Advise community to avoid using

contaminated springs for



quality changes may be

long-term if the aquifer

becomes contaminated.

Maintain well head or

spring head protection

areas.

quality is not

compromised.

drinking during and after


been verified.


users about possible contamination of the

aquifer following floods,

irrespective of localised flooding at the collection

area.

Flooding reducing

availability of safe

water.

Eye of the spring

submerged under

floodwater.

No access to water

source.

Develop springs outside

flood prone areas, where

possible.

Implement land

management activities to reduce severity of


adequate drainage, reforestation, retention

basins.

Prepare flood risk map

and update as necessary.

Investigate alternative

sources.


users of potential

consequences of

flooding on the quality

of water and actions to

be taken in such circumstances.

Rainwater collection



Collection or storage

facilities are inundated.

Rainwater collection or

storage systems become

inaccessible.

Introduction of contamination into the

rainwater storage

system.

Avoid using

underground storage

facilities in flood prone

areas, and ensure proper

design and maintenance of all storage and

collection facilities to

prevent contamination.

Raise level of storage

tanks where possible.

Consider accessibility

issues when designing rainwater collection for

an area to ensure that

some supplies are accessible in floods.

Consider increasing capacity.


sources.

Clean and disinfect all

storage and collection

facilities, after

inundation in flood

water, before use.

Strengthen collection

and storage facilities.

Plan for collection of

increased silt load.


Monitor for microbial

contamination where

possible.


the users about possible


system following floods,

including contamination of the stored water.

Provide information

about increased silt load

and increased capacity.

Key issue: Groundwater recharge increases Utility-managed piped water supplies



Potential deterioration in

the quality of

groundwater sources as a

result of more rapid

transport of water in

subsurface, and potential

compromising of

sanitation systems.

Rising groundwater

levels flood sanitation

systems, creating

pathways for the

potentially rapid

dispersal of

contaminants into

groundwater.

Rising water level

mobilize microbial and

chemical contaminants.

Ingress of groundwater

into treated water

supply, potentially

contaminating water.


risk from consuming the

water.


update water safety

plans.

Investigate increasing

protection zones around

wells, to reduce

contamination sources.

Adapt water treatment to

respond to changing

water quality.

Increase the depth of

well intakes, where

possible.

Move towards

continuous positive

pressure in system.

Investigate the benefits

of placing increased

reliance on groundwater systems in areas of rising

groundwater, provided

appropriate treatment

can be added.

Maintain positive

pressure in pipes

wherever possible

Pipe maintenance

programme to fix leaks

in pipes.



for groundwater sources

based on groundwater

level.


groundwater levels and

quality to increasing rainfall, to identify

vulnerability.

Monitor water quality in

at-risk pipe networks


resource managers,

water and sanitation

professionals, public

health professionals and

consumers about

possible groundwater

contamination issues and

health impacts.


consumers of the need for household water

treatment.


when appropriate.

Increase vulnerability of

flooding (see flooding).





the quality of



transport of water in subsurface, and potential

compromising of

sanitation systems.

Rising groundwater

levels flood sanitation

systems, creating

pathways for the

potentially rapid dispersal of

contaminants into

groundwater.

Rising water level

mobilizes microbial and

chemical contaminants.

Ingress of groundwater into treated water

supply, potentially

contaminating water.


risk from consuming the water.



wells, to reduce



respond to changing

water quality.


update water safety

plans.

Investigate the benefits of placing increased

reliance on groundwater

systems in areas of rising groundwater, provided

appropriate treatment

can be added.

Increase the depth of

well intakes, where

possible.

Move towards

continuous positive

pressure in system.



technical and

administrative

assistance.

Maintain positive

pressure in pipes

wherever possible.

Pipe maintenance

programme to fix leaks

in pipes.





level.



quality to increasing

rainfall, to identify

vulnerability.





from rising.


health messages with

advice about dealing

with the issues,

including the need for

household treatment and

boil water notices where

appropriate.

This may be done by


door visits, radio and television

announcements, and by

posting notices in prominent places in the

community.

Increase vulnerability of

flooding (see flooding).

Public standpipes



See utility- and community- managed piped water supplies




Potential deterioration in the quality of


result of more rapid transport of water in


compromising of

sanitation systems.

Significant risk to the health of consumers.

Increase in groundwater level could also lead to a

reduction in the

vulnerability of

protected wells and

provide a more

sustainable water supply

than alternative water

supply options.

Investigate increasing protection zones around

wells, to reduce



respond to changing

water quality.

Set intakes at greater

depth or modify

pumping regimes, where

feasible.

In the event of a

decrease in the

vulnerability of

protected wells, an

increase in the reliance

on groundwater sources

should be considered.


technical and

administrative assistance.

Act upon sanitary risk

inspections.

Design and implement a monitoring programme


based on groundwater level.





vulnerability


Prevent latrines being constructed nearby.

Raise awareness among users of the wells about



and the need for

household water

treatment.


where appropriate.


procedures for when

water is safe.

This may be done by



boreholes and removing

the notices when the water is safe.

In areas where there is a high density of boreholes




developing an

association of well


to manage and monitor

wells and provide guidance to users.

Raise awareness of well use in emergency

situations.

Protected springs



Increased flow of the

spring may cause

damage to the existing

infrastructure.

Spring protection

damage, leading to

increase vulnerability of

the spring to ingress of surface contamination.

Significant risk to the health of users of the

spring.

Investigate installing

additional drainage or

overflow pipes to

alleviate pressure build-up.

Design and construct spring box storage to

account for increase

flows.

Repair structure and

reinforce as necessary to

reduce risks identified by

sanitary inspection.


support unit to provide technical and

administrative

assistance.

Sanitary inspection. Communicate risk to the

users of the spring.

Advise household

treatment as necessary.


the quality of



transport of water in


compromising of sanitation systems.

Significant risk to the

health of users of the

spring.



source, to reduce



respond to changing water quality.

Act upon sanitary risk

inspections.



technical and

administrative assistance.





level.

Monitor the response of spring discharges to


users of the springs

about risks from water

quality changes and the

need for household water

treatment.

This may be done by adding warning labels to






vulnerability.


contaminated springs

and removing the notices

when the water is safe.

Key issue: Increase in extreme rainfall events

One of the main impacts of more extreme rainfall events will be flooding, so these tables build on the vulnerabilities of general flooding with

vulnerabilities associated with heavy rainfall and flash flooding.

Utility-managed piped water supplies



See also key issue: Flooding increases

Damage to

infrastructure.

Potential failure of the

drinking-water supply

system and loss of

service.

Public health risk from

contaminants entering

the water distribution system through damaged

pipes.

Design or adapt reservoir

overflows and spillways

to cope with larger

flows.

Adopt higher design

standards for

infrastructure to take more frequent extreme

weather events into

consideration.


update water safety

plans.

Response plan after

flooding to assess and


damage.

Plan for emergency

supplies of drinking-

water to be available in the event of system

failure.


stations.

Rain gauging.


Enhanced inspection of infrastructure.



contamination during and

after extreme rainfall

events.


water engineers of risks from water quality changes

during extreme rainfall

events, and how to manage the risk.

Disseminate health

advisory notices to the

public with advice about

dealing with the risks.


procedures to notify public


Issue boil water notices if

appropriate.

Possible mechanisms






announcements.

Treatment and pumping

systems unable to work

if electricity is affected.



system and loss of

service.

Have reservoirs

throughout pipe network

to store treated water and

provide gravity fed water.


update water safety

plans.

Fill local reservoirs prior

to large storms to

provide gravity flow.


stations.

Rain gauging.



infrastructure.




after extreme rainfall events.



from water quality changes


events, and how to manage

the risk.

Disseminate health advisory notices to the







appropriate.

Possible mechanisms include posting leaflets,


radio and television announcements.



Increased erosion

leading to more polluted

run-off, with silt and

nutrients.

Increase in suspended

sediment loads may


capacity of the water

treatment facilities.



the water distribution system.

Land management –

minimize erosion with

planting schemes, buffer

strips and storm water

management.


update water safety

plans.

Maintain vegetation in

buffer strips next to

rivers.

Monitor water quality

and adapt treatment

processes to ensure that

water quality is not

compromised, such as by

increasing sedimentation time and improving

filtration systems.




after extreme rainfall

events.



from water quality changes during extreme rainfall

events, and how to manage

the risk.

Disseminate health








appropriate.

Possible mechanisms


door-to-door visits, and radio and TV

announcements.

Increased risk of

landslides on steep slopes causing damage

to infrastructure.


drinking-water supply system, and loss of

service.

Build treatment works

and pipe networks away from slopes that are at

risk of slippage.

Reinforce slopes where

there is a risk of slippage that may damage

infrastructure.


stations.

Rain gauging.

Raise public awareness on

risk of contamination during and after extreme

rainfall events.





the water distribution

system through damaged

pipes.

Reduced access to the

affected areas.


update water safety

plans.

Implement leakage

reduction plan, as

leakage can contribute to

landslides.


infrastructure.



from water quality changes


events, and how to manage the risk.





procedures to notify the

public when the water is

safe.


appropriate.

Possible mechanisms




announcements.

Groundwater quality,

particularly at shallow

depths, may deteriorate. Increased lateral flow in

soils may also spread

contamination.





update water safety

plans.

Consider constructing

deeper wells.

Ensure that wells are

sealed to several metres

below the water table.


and adapt treatment

processes to ensure that water quality is not

compromised.


water resource managers

and water engineers about the potential for lateral

transport of pathogens and

subsequent contamination of water.



Consider alternative

sources.

Disseminate health




Develop communication procedures to notify the


safe.


appropriate.





See also utility-managed piped water supplies

Increased risk of


to infrastructure.


drinking-water supply system, and loss of

service.




pipes.

Reduced access to the

affected areas.

Where possible, avoid

installing pipes on slopes that are at risk of

slippage.


update water safety

plans.



infrastructure.



technical and administrative

assistance.


the community about the damage that landslides

can cause to

infrastructure and the potential effect on the


Public standpipes




See also utility- and community-managed piped water supplies

Increased risk of

landslides on steep

slopes causing damage

to infrastructure.

Loss of water supply to

the standpipes.

Permanent loss of standpipe.

Site standpipes away

from slopes that are at

risk of slippage.


there is a risk of slippage

that may damage

infrastructure. If standpipes are located

on at-risk slopes, ensure

proper drainage.

Local professional

management (water

kiosks) rather than free

public standpipes will

create positive incentives

for management and protection of the

infrastructure.


the community about the

damage that landslides

can cause to infrastructure and the

potential effect on the






Increased risk of

landslides on steep


to infrastructure.

Permanent loss of

borehole or well as a

result of it being buried

under the landslide.

Damage to the structure of the borehole or well,

Build wells away from

slopes that are at risk of

slippage.



that may damage

infrastructure.

Monitor microbial

quality of water after the

well or borehole has

been renovated.



damage that landslides

can cause to wells and

boreholes.



leading to a temporary

loss of supply.

Groundwater quality,

particularly at shallow

depths may deteriorate.

Increased lateral flow in


contamination.



water.



wells, to reduce

contamination of

sources.

Site well away from

latrines and other

sources of groundwater

pollution.

Ensure that wells are

sealed to several metres

below the water table.


Monitor microbial

quality of water.



potential for lateral

transport of pathogens,

and the potential for

contamination of water during and after extreme

rainfall events.



benefits of household

water treatment.


procedures for notifying the community when the

water is safe.

Protected springs




Increased risk of


to infrastructure.

Permanent loss of spring

as a result of it being buried under the

landslide.

Damage to the structure

of the spring, leading to

a temporary loss of supply.

Construct collection and

storage infrastructure, and fencing from durable

materials to reduce

damage during extreme

events. Ensure they are

properly designed and

maintained.

Reinforce spring

infrastructure and surrounds to prevent

slippage.

Sanitary inspection. Raise awareness among

the community about the risk of landslides and the

damage that they can

cause to springs.


the community about the benefits of household





water.

water treatment.


procedures for notifying

the community when the

water is safe

Groundwater quality, particularly at shallow

depths may deteriorate.

Increased lateral flow in


contamination.

Quality of the water from the spring

deteriorates. Water

quality changes may be

long term if the aquifer

becomes contaminated.

Investigate alternative sources, if appropriate

and possible.

Properly seal abandoned wells to protect

groundwater quality.

Maintain well head or

spring head protection

areas.

Water quality monitoring after a flood

to verify that water

quality is not

compromised.

Advise the community to avoid using

contaminated springs for

drinking during and after


been verified.


users about possible


aquifer following floods, irrespective of localized

flooding at the collection

area.





Increased risk of

landslides on steep


to infrastructure.

Permanent loss of

rainwater collection

system as a result of it

being buried under the landslide.

Ensure appropriate

design, construction and

maintenance, and use

durable materials. Ensure sufficient

overflow or bypass

Replace roof material

where appropriate.


Make regular checks to

ensure the infrastructure is not damaged.


the owners and users of

rainwater collection

systems about the damage that landslides

can cause to




of the collection system,

leading to a temporary

loss of supply.

facilities.

infrastructure.

Key issue: Run-off increases

Similarly to the impacts of more extreme rainfall events, one of the main impacts of increased run-off will be flooding, so these tables build on the

vulnerabilities of general flooding.

Utility-managed piped water supplies




Erosion exposing and

damaging pipe work.



system and loss of

service.




pipes.

Land management –

compaction of soils and

planting above pipes,

under paved roads etc.


update water safety

plans.

Implement leakage

reduction plan, as


landslides.


stations.

Rain gauging.


infrastructure.



from water quality

changes from run-off

and how to manage the risk.







safe.


if appropriate.

Possible mechanisms




announcements.



Increased erosion


run-off, with silt and

nutrients.

Increased suspended

sediment loads may


capacity of the water





Land management –


planting schemes, buffer

strips and storm water

management.


update water safety

plans.



rivers.


and adapt treatment

processes to ensure that

water quality is not



filtration systems.



from water quality

changes from run-off

and how to manage the

risk.

Disseminate health

advisory notices to the public with advice about





safe.

Issue boil water notices if appropriate.

Possible mechanisms




announcements.

Community-managed piped water supplies (see also utility-managed piped water supplies)




Increased erosion


run-off, with silt and nutrients.

Increased suspended

sediment loads may

exceed the treatment capacity of the water




the water distribution

system.

Land management –


planting schemes, buffer strips and storm water

management.


update water safety

plans.



rivers.


support unit to provide technical and

administrative

assistance.


and adapt treatment

processes to ensure that water quality is not



filtration systems.



risk of contamination during and after extreme

rainfall events.

Disseminate health






community when the

water is safe.


if appropriate.

Possible mechanisms

include posting leaflets, door-to-door visits, and


announcements.

Public standpipes (see also utility- and community-managed piped water supplies)




Erosion damaging

standpipe.

Destruction of the

standpipe and loss of

service.


contaminants entering the standpipe.

Land management –


planting schemes, buffer strips and storm water

management.

Use durable materials in

construction.

Maintain conditions

which mitigate erosion,

e.g. compaction of soils and plants in buffer

strips.



technical and

administrative

assistance.

Sanitary survey. Raise awareness among


damage that erosion can cause to infrastructure,

and the potential effect

on the water supply system.

Disseminate health





procedures to notify the community when the

water is safe.


if appropriate.

Possible mechanisms




announcements.





Erosion Permanent loss of

borehole or well.


of the borehole or well,

leading to a temporary loss of supply.



the standpipe.

Ensure that well heads

are properly designed to

prevent erosion damage that may increase

infiltration.

Use compaction of soils

and planting around

infrastructure to increase

durability of structures.

Maintain conditions

which mitigate erosion


strips.

Monitor microbial

quality of water after the

well or borehole has been renovated.



damage that erosion can cause to wells and

boreholes.



community when the

water is safe.

Protected springs




Backfilled areas become

eroded leading to

contamination in

recharge area.


of the spring, leading to

a temporary loss of

supply.


contaminants entering the spring.

Ensure that collection

infrastructure is properly

designed to prevent

erosion damage that might compromise the

integrity of the structure.

Ensure that fencing and

ditches are in good

repair; drain surface

water. Re-lay grass.

Sanitary survey.

Microbiological

monitoring of the spring water after rehabilitation.

Raise awareness of

possible water

contamination as a result

of erosion damage.





Erosion around storage

area.


of the rainwater storage

tank, leading to a temporary loss of

supply.



the storage tank.

Ensure that area around

storage infrastructure is

designed to mitigate erosion; for example,

compaction of soils and

plants in buffer strips.

Maintain conditions

which mitigate erosion


strips.

Sanitary survey. Raise awareness among

users about the risks to

rainwater infrastructure from erosion.

Key issue: Water availability decreases Utility-managed piped water supplies



Insufficient water for

demand.

Water shortages and

potential for water

rationing.


inappropriate water

saving in the home.

Low pressure in system may allow ingress of

contamination into the

water distribution network.

Intermittent water

supplies and pressure

changes in the

distribution network lead

to damage of the

infrastructure.


update water safety

plans.

Improve efficiency of

water use in non-

domestic water use.

Increase water storage capacity to provide

supply over extended dry

periods.

Investigate alterative

water sources and water

harvesting methods.

Investigate water reuse

schemes.

.

Develop emergency

water plan for times of extreme scarcity, such as

linkages to other sources

or emergency tank supplies.

Decentralization of

water systems may allow

for quicker adaptation to

local conditions.

Pipe maintenance

programme to reduce

leaks.

Prioritize allocation for

domestic use.

Monitor water pressure

in pipes to aid in

detection of leaks.

Monitor water use.

Water resource

monitoring.

Implement education

programme to reduce

water demand.

Raise awareness of reuse

of wastewater for

agricultural and

industrial purposes.

Implement discussions

with other water users

such as irrigators to manage the resource

cooperatively.

Promote the importance

of hygiene.

Review water pricing

policy as a method of

demand management.



Integration of systems

may protect from water

shortages. Conjunctive

water use.

More pronounced and

changing seasonality of

water supplies.

Increased levels of


source water, particularly at the end of

periods of drought.

Insufficient water to

meet demand.

Low pressure in system

may allow ingress of

contamination into the

water distribution network.

Intermittent water supplies and pressure

changes in the


to damage of the

infrastructure.


update water safety

plans.

Increase water storage

capacity to provide

supply over extended dry

periods.

Increase infiltration to

groundwater when water

is available.

Investigate

supplementary water

sources.

Pipe maintenance

programme to reduce

leaks.


domestic use.

Water resource

monitoring.


with other water users

such as irrigators to manage the resource

cooperatively.

Implement education

programme to reduce

water demand.

Raise awareness of reuse

of wastewater for

agricultural and industrial purposes.

Less water used for

critical domestic

purposes.


inappropriate water

saving in the home.

Research low-water

usage appliances for

non-critical domestic

use.

Maintain a minimum

domestic supply.

Water use surveys. Promote the importance

of hygiene and raise

awareness among the

public about low water

use systems.

Decreased water flow

may result lower quality

Quality of the raw water

may deteriorate to the


update water safety

Seasonal forecasting. Water resource

monitoring.


water engineers of



source water; for

example, increase in

turbidity.

point where it exceeds

the treatment capacity of

the water treatment

facility.

Public health risk from consumption of the

water.

plans.

Redesign treatment plant

and improve filtration

systems.

Monitor water at inflow

and adjust treatment

accordingly.

possible contamination

issues resulting from

decreased water flow.


may lower levels in

reservoirs and damage

infrastructure or restrict

use.


the quality of the stored

water.

Dams may be weakened

by prolonged low-

storage levels.

Investigate use of

underground storage.

Adapt intake

infrastructure to handle

low flows.

Adapt reservoirs to

handle low water levels.

Adjustable intakes to

draw from optimum

levels in the reservoir.

Water resource

monitoring.


of hygiene and raise

awareness among the

public about low water

use systems.

Falling groundwater levels affect productivity

of supply wells.

Wells become unproductive, leading to

a loss of water supply.

Evaluate the vulnerability of wells to

seasonal and sustained

drought.

Manage groundwater

abstraction to maintain

drinking-water supply.

Investigate developing

deeper wells.

Promote rainwater harvesting to enhance

groundwater recharge.

Seasonal forecasting. Monitor the current relationship between


climate.

Implement discussions with other water users

such as irrigators to

manage the resource cooperatively.

Implement education

programme to reduce

water demand.


all stakeholders of reuse

of wastewater for agricultural and

industrial purposes.



Investigate the reuse of

wastewater for artificial




Water becomes too

saline to use.

Loss of water supply. Develop, implement and

update water safety

plans.

Determine the cause and

degree of vulnerability.

Investigate treatment

systems that can treat

salinity.


water sources.

Promote rainwater

harvesting to enhance


Investigate the reuse of



Investigate the potential

for conjunctive use of

water sources (blending

and dual multiple

sources).

Monitor salinity levels. Start discussions with

irrigators and other

aquifer users about the

risks to water quality

from different water

practices.

Reduced moisture in

soils may cause movement, damaging

infrastructure.

Movement and

infrastructure damage.

Ingress of contamination

into water system

Design for movement,

e.g. by using shorter lengths of pipes; or use

non-reticulated systems

on site.

Adapt maintenance

programme to identify breakages.

Monitor integrity of

pipes and reservoir structures.



through damaged pipes.


consumption of the

water.

Leakage management

programme.

Community-managed piped water supplies (see also utility-managed piped water supplies)




demand, or increased

seasonality of water.

Water shortages and

potential for water

rationing.


inappropriate water

saving in the home.

Low pressure in system

may allow ingress of contamination into the

water distribution

network.

Intermittent water

supplies and pressure

changes in the


to damage of the

infrastructure.

Restrict water supplies

and switch pipes off.


update water safety

plans.

Improve efficiency of

water use in non-

domestic water use.

Increase water storage

capacity to provide supply over extended dry

periods


water sources and water

harvesting methods.

Investigate water reuse

schemes.

Pipe maintenance

programme to reduce

leaks.


domestic use.



technical and administrative

assistance.

Monitor for microbial

quality of water.

Educate communities

about reliable water

sources: how to select

them, what makes them

reliable, etc.


the community about

issues of quality and

infrastructure damage associated with

intermittent piped

supplies.


of hygiene.

Implement education

programme to reduce

water demand.



Develop emergency

water plan for times of

extreme scarcity, such as

linkages to other sources

or emergency tank

supplies.

Integration of systems

may protect from water shortages.

Shared water use.


may result in increased

turbidity and decreased

dilution of pollution.

Quality of the raw water

may deteriorate to the

point where it exceeds

the treatment capacity of

the water treatment facility.

Public health risk from consumption of the

water.


update water safety

plans.

Redesign treatment plant and improve filtration

systems.



technical and

administrative

assistance.

Water resource

monitoring.

Monitor water at inflow

and adjust treatment accordingly.


the community of

possible contamination

issues resulting from

decreased water flow.

Disseminate health

advisory notices to the public with advice about



procedures to notify

community when the

water is safe.

Issue boil water notices if appropriate.

Public standpipes (see utility- and community-managed piped water supplies)



The vulnerabilities, impacts and adaptations that are relevant to, and will affect the operation of public standpipes have been covered in the tables dealing with

utility- and community-managed piped water supplies.





demand

Water shortages and

potential for water

rationing.


inappropriate water

saving in the home.


and supplementary water

sources and water harvesting methods, such

as rainwater collection

and water reuse.

Prioritize water use for

drinking.

Investigate methods for

the artificial recharge of groundwater

Investigate catchment management practices to

promote infiltration.

Consider deepening the

wells and boreholes.

Ensure high levels of

maintenance on wells to

avoid unnecessary losses of water at the point of

use.

Monitor water use at

well for user pays

scheme, and assist in demand management.

Monitor the ability of

wells to cope with

current droughts

Implement education

programme to reduce

water demand.


of hygiene.

Educate communities




reliable, etc.

Increased use of viable

wells causes increased

wear and tear, and

increased water demand.

Damage to well or

borehole increases the


entering water source.

Determine the degree of

vulnerability through

investigating linkages

between climate and


maintenance on in-

demand wells.

Sanitary survey.


wells to cope with


with other users of the

aquifer such as irrigators

and private well owners




consumption of the

water.

groundwater, e.g.

residence times.

current droughts. to manage the resource

cooperatively.

Less water available for

hygiene and cleaning.


inappropriate water

saving in the home.

Research cleaning and

hygiene methods that

have low-water usage.

Water use surveys. Raise awareness of the

importance of hygiene.

Groundwater levels

dropping, especially during a dry period or

season.

Water shortages and

potential for water rationing.


inappropriate water

saving in the home.

Increased risk of


water at the end of the drought.

If supply from the well is

already variable, consider that the current

well may need to be

extended or new deeper

wells may need to be

installed.

Install relief wells that

can be uncapped for easy

use in dry periods to supplement existing

wells.


vulnerability.

Concentrate water

quality monitoring during periods of high

risk at the end of the

droughts.

Start discussions with

irrigators and other aquifer users about the



practices

Water quality

deteriorates with increasing salinity.

Loss of water supply. Determine the cause and

degree of vulnerability.


systems that can treat

salinity.

Identify alternative, non-

saline sources.

Promote rainwater

harvesting to enhance

Monitor salinity levels. Start discussions with

irrigators and other aquifer users about the



practices.




Investigate potential for

re-use of treated



Protected springs




demand, including

seasonal shortages.

Water shortages and

potential for water

rationing.


inappropriate water

saving in the home.

Investigate alterative and

supplementary water

sources and water

harvesting methods such

as rainwater collection

and water reuse.

Prioritize water use for

drinking.

Investigate methods for

the artificial recharge of

groundwater.

Investigate catchment

management practices to

promote infiltration.


maintenance on springs

to avoid unnecessary

losses of water at the

point of use.

Monitor water use at

spring for user-pays

scheme, and assist in

demand management.


springs to cope with

current droughts, and

map vulnerable springs.

Implement education

programme to reduce

water demand.

If appropriate, review

water pricing policy as a

method of demand

management.

Educate communities about reliable water


them, what makes them reliable, etc.

Increased use of viable

springs increases water

demand.

Damage to the spring

increases the risk of

contamination entering

the water source. Public

health risk from

consumption of the water.




between climate and

groundwater, e.g.

residence times.


maintenance for spring

infrastructure.


spring to cope with

current droughts.


with other users of the

aquifer such as irrigators

and private spring

owners to manage the

resource cooperatively.




hygiene and cleaning.


inappropriate water

saving in the home.

Research cleaning and

hygiene methods that

have low-water usage.

Water use surveys. Raise awareness of the

importance of hygiene

and low water methods

available.

Springs become less

productive.

Loss of water supply.

Public health risk from inappropriate water

saving in the home.

Install storage facilities

to maximize collection.

Investigate other water

sources.




between climate and

groundwater, e.g.

residence times. Ensure

ability to cope with current droughts.

If the spring is known to be dependent on local

weather conditions,

consider that the spring

may have a limited

lifespan.


maintenance for spring

infrastructure.


spring to cope with

current droughts.

Implement a demand

management plan for

household water use and for other uses of the

spring and the aquifer.

Raise awareness of the

importance of hygiene

and low water methods

available.

Water quality

deteriorates with

increasing salinity.

Loss of water supply. Determine the degree of

vulnerability.

Identify alternative, non-

saline sources.


that treats salinity.

Monitor salinity levels in

groundwater.

Start discussions with

irrigators and other

aquifer users about the


from different water practices.




Reduced rainfall or

changes in seasonality of

rainfall.

Reduced water

availability with the

potential loss of supply.

Increase size of

collection and storage

facilities to maximize

collection at other times.


and supplementary water

sources such as water

reuse.

Ensure that system is

maintained so that it is

functions well when it

rains.

Monitor water use to

assist in demand

management.

Implement education

programme with the

community of users to

reduce water demand.

Educate communities




reliable, etc.

Reduced water quality as

a result of build-up of

contaminants on

surfaces.


consumption of the

water.

Divert “first-flush”

rainwater for uses other

than drinking.

Treat water before

drinking.

Sweep collector surfaces

during long dry spells.

Monitor microbial

quality of water where

possible.

Educate the users about

quality issues of “first-

flush” rainwater.

Key issues: Flooding increases; increase in extreme rainfall events; run-off increases

For sanitation facilities, there are many similarities between the impacts of extreme rainfall events, increased run-off and flooding, and hence these

three scenarios have been combined here in the guidance notes for increases in flooding.

Sewers



Infiltration of flood

water into sewer, leading

to plug flow of

pollutants and resuspension.

Overloading of treatment

works.

Pollution of water resources downstream.

Ingress of silt.

Use sustainable urban

drainage systems and

separate sewers.

Encourage decentralized

systems.

Clean sewers regularly.

Clean drains regularly

especially just before wet season.

Monitor silt levels,

blockages, cross-

connections and so on, in

drains and sewers.

Stop illegal connections

to foul sewers.

Inundation of sewerage

system including

treatment works.


the system.

Install flood defences,

catchment management.

Encourage decentralized

systems.

Invest in emergency

response equipment e.g.

mobile pumps kept in separate location.

Rehabilitation plan.

Rising receiving water

levels.

Overloading of sewers,

leading to backing-up.

Shallow sewers.

Flap valves.



High flows cause sewers

to flood into

environment and houses.

Decrease diameter of

pipes to attenuate and

store water.

Separate sewage and

stormwater systems.

Consider use of small

bore or other low-cost sewerage options at local

level to reduce costs of

separate systems.

Design decentralized

systems to minimize

impact of local flooding.

Education about hygiene

and cleaning up after

flooding.

Treatment and pumping systems cannot work if

electricity is affected.

Ensure that sewers are gravity flow wherever

possible. Low-cost and

shallow sewers have much lower pumping

requirements.

Local decentralized treatment will reduce

pumping costs and

enable local responsive management when

system is vulnerable to

damage.

High flows wash out

sewage treatment plant

and sewage pumping

stations.

Large populations

affected by flood

damage and

contaminated

floodwater.

Use sewage overflow

routing or storage to

protect treatment

processes and other

infrastructure.

Design decentralized treatment to minimize

damage to locality of

flooding.

Have spare parts

available.

Local management of

decentralized systems

may improve response

time for urgent maintenance and flood

protection.



Decentralize wastewater

systems to mitigate the

number of people

affected by shut downs

of sewers resulting from flooding.

Gravity only systems, shallow sewers.

Erosion exposing and

damaging pipe work,

especially simplified

sewerage.

Site pipe away from

drainage channel.

Compaction of soil and

planting above sewers,

under paved roads etc.

Adopt more conservative

design standards for

infrastructure to take more severe and more

frequent extreme

weather events into

consideration (the more

expensive option), or

have systems that can be

quickly and cheaply

replaced.

Low-cost sewers can be

more easily maintained

or replaced when

damaged, but are more

vulnerable to erosion.

Have spare parts available.

Increased risk of

landslides on steep slopes.

Damage to

infrastructure.

Build treatment works

and sewer networks away from slopes that

are at risk of slippage.



infrastructure.


the damage that landslides can cause to

infrastructure.



Implement leakage

reduction plan, as


landslides.

Put in urban drainage.

Flooding causes damage to bridges and other

structures that support

pipes.

Adopt higher design standards for

infrastructure to take

higher and more frequent

floods into

consideration.

Install sewers on bridge

least prone to being

damaged by floods.

Install storm water tanks

to provide overflow

storage.

Have spare parts available.

Raise awareness about potential dangers

associated with physical

infrastructure failures.

Septic tanks



Back flow of sewage

into the house.

Install non-return valve

that can be shut in event

of a flood; do not use the

septic tank again until

waters have receded.

Regular emptying

services to minimize

faecal sludge build-up.


potential health issues

associated with sewage.



Inundation of the

system, resulting in

contamination of

surrounding area with

sewage.

Where possible, site tank

away from water supply.




Flooding of septic tank

resulting in accumulation of silt.

Design to prevent

ingress of silt.

Septic tanks and pump

chambers can fill with silt and debris, and must

be pumped out and

cleaned after a flood.

Ensure adequate access

to tanks so that they can

be cleaned.

Flotation. Structural damage to

tank, for example from movement.


construction of tanks.

It is important that tanks

are full of water during a flood to prevent damage

to the infrastructure.

However, lids need to be properly fitted and

secured to prevent

sewage overflow.

Education and increased

awareness of issues

surrounding damage and

when to replace.

Increased risk of

landslides on steep

slopes.

Damage to

infrastructure.

Avoid using soakaways

on slopes that are at risk

of slippage, as they can

contribute to landslides

(or ensure they are piped

away from the slope).



that may damage

infrastructure.


the damage that

landslides can cause to

infrastructure, and the

potential contamination

issues related to damage.



Erosion of soil around

the tank and absorption

field.

Damage to

infrastructure. Reduced

efficacy of the

absorption field.

Planting of grasses and

shrubs on the absorption

area, and around the

tank, to reduce erosion.

Repair erosion damage and sod or reseed areas

as necessary to provide

turf grass cover.

Build bunds (banks,


flow away from system.

Check the vegetation

over the septic tank and

soil absorption field after

flooding.

Flooding of the

absorption field with

sewage sludge.

Install non-return valve

that can prevent flow to

the field in event of a

flood.

Inundation of the soakaway.

Delay using septic tank until flood waters and

groundwaters have

receded.

Educate about avoiding using the absorption

field until groundwaters

and floodwaters have receded.

Raise awareness of signs

of failure of an

absorption field, and

how to fix it or construct

a new one.

Improved pit latrines



Pit overflowing or

inundated; very mobile

contamination.

Faeces leaving pit and

causing pollution

downstream.

Silt and solids entering pit and filling it.

Design pit to allow regular

emptying and post-flood

rehabilitation to remove silt.

Proper pit covers to prevent material flowing out in a

flood.

Investigate overflow

mechanisms to filter water

to reduce pressure build-up.

Where possible, site latrine

away from water supply, and away from areas prone

to flooding.

Build pit latrine

superstructure at the same

level as the houses, as these usually are above normal

flood level.

In urban areas, consider

small pits which need

regular (monthly or less)

emptying to minimize the

amount of faecal matter

exposed to flooding.

Consider if dry or

composting latrines or sewerage is appropriate.

Regular pumping or

emptying of pit latrine

(particularly in urban

setting).

Monitoring and

regulation systems

should focus on

emptying and faecal

sludge management as well as construction of

latrines – to ensure that

systems are in place.



of drinking-water

supply and need for

regular emptying.



Increased intentional

emptying of pits during

floods.

Widespread

contamination with

faeces.

Regular pumping or

emptying of pit latrine


setting).

Monitoring and

enforcement systems

should focus on

emptying and faecal

sludge management, as

well as construction of latrines – to ensure that

systems are in place.





potential contamination of drinking-water

supply.

Inundation or erosion. Collapse of latrine. Site latrine away from

drainage channel.


construction to protect pit

covers.

Proper compaction of soil

around the latrine and presence of adequate base

and earth filling to protect

pits, pit covers and slabs.

Install robust upper

foundations, collar and

footing to protect from

erosion and flooding

damage.

Small pits in urban areas to

minimize risk of collapse.

Build bunds (banks, dykes

or levees) to divert flow away from latrine.

Regular maintenance

essential to limit

vulnerability to collapse.

Hygiene promotion.

Education on regular

maintenance

requirements.



Planting of shrubs around

the pit to reduce erosion

damage.


design standards for infrastructure to take higher

and more frequent events

into consideration (more expensive), or have systems

that can be quickly and

cheaply replaced.

Damage to the

superstructure.

Make more durable,

especially the bottom 30cm,

or choose a cheaper

temporary option that can

be reinstalled rapidly.

Latrine not accessible. Find a new site, not subject to such frequent flooding,

or construct temporary

latrines in refuges.

Pit latrines sited in flow paths.

Filling up with water or overflowing.

Insert a bund. Seasonal emptying.

Increased risk of

landslides on steep

slopes, causing damage

to infrastructure.

Avoid building pit latrines

on slopes that are at risk of

slippage.


there is a risk of

slippage that may

damage infrastructure.


the damage that


infrastructure, and the potential contamination

issues associated with

damages.

Composting or dry latrines



Pit inundated. Faeces leaving chamber,

leading to pollution in

the environment.

Design toilet to be

appropriate to flooding

levels (e.g. above ground

chambers, rather than

small pits).

Capacity to restart

composting following

event. Redress moisture

balance.

Ensure that users know

they should keep

moisture out after

flooding.

Increased intentional emptying of pits during

floods.

Widespread contamination with

faeces.

Awareness of importance of not

emptying during floods

where there is no use of

compost.

Inundation or erosion. Collapse of latrine. Site latrine away from

drainage channel.


construction to protect

pit covers.

Proper compaction of

soil around the latrine

and presence of adequate

base and earth filling.

Build bunds (banks,


flow away from latrine.

Planting of plants around the pit to reduce erosion

damage.


design standards for

infrastructure to take

Regular maintenance

essential to limit

vulnerability to collapse



more severe and more

frequent extreme

weather events into

consideration (more

expensive), or have

systems that can be quickly and cheaply

replaced.

Damage to the

superstructure.

Make more durable,

especially the bottom

30cm, or choose a

cheaper temporary

option that can be

rapidly reinstalled.

Latrine not accessible. Find a new site, not subject to as-frequent

flooding, or construct

temporary latrines in refuges.

Pit latrines sited in flow

paths.

Filling up with water or

overflowing.

Insert a bund. Seasonal emptying.

Increased risk of

landslides on steep

slopes, causing damage

to infrastructure.

Avoid building latrines

on slopes that are at risk

of slippage.



that may damage

infrastructure.


the damage that


infrastructure, and the


issues associated with damages.

Key issue: Groundwater tables rising

Sewers



Sewer surrounded

by water.

Overloading.

Damage to sewer

(scouring or washout of bedding, and flotation

leading to cracking of

the sewer pipes).

Do not locate sewers in

soils which are regularly

waterlogged.

Low-cost and shallow

sewers may be less

susceptible and above groundwater levels.

Septic tanks



Flotation of septic tank. Damage to

infrastructure.

If groundwater rises

above the bottom of the

tank, the tank will need

to be secured to prevent

floating during pump-

out.

Education and increased

awareness of issues

surrounding damage and

when to replace.

Inundation of soakaway. Increased potential for

contamination of groundwater.

Treatment of sewage by soil in soakaways may

be reduced.

Use shallower

infiltration trenches or introduce artificial

wetlands or reedbed

systems to improve effluent treatment.


and groundwater levels.

Education to increase

awareness of the risks of sewage upwelling if

soakaways are

waterlogged.

Ensure that septic tanks

are emptied regularly.

Septic tank fills and

backs up.

Where possible, site

system away from water

supply.

Design septic tank

systems in conjunction

with drainage to lower the groundwater table.

Introduce trees and other

plants to improve

drainage and increase

water loss by

transpiration.


awareness of possible

contamination of water

resources.




Inundation of the pit from below.

Contamination of groundwater and soil,

potentially reaching

drinking-water resources.

Provide protected water supply.

Consider options: shallower pits and more

frequent emptying;

dry composting latrines;

sewerage.

Regular pumping or emptying of pit latrine


setting) – link to smaller pit sizing.

Monitor drinking-water quality.

Education to increase marketing and user

education of alternatives.

Inundation of pit. Pit collapse. Build round pits instead

of square to increase

stability.


construction to protect pit covers.


the dangers of unstable

pit latrines, and under

what conditions these

might occur.



Proper compaction of

soil around the latrine

and presence of adequate

base and earth filling to

protect pits, pit covers

and slabs.

Install robust upper

foundations, collar and footing to prevent

collapse.

Small pits in urban areas

to minimize risk of

collapse.

Introduce trees and other

plants to improve drainage and increase

water loss by

transpiration.

Key issue: Water availability decreases Sewers



Less water available. Low or intermittent

flows may lead to

blockages building up

more quickly.

Increase attention to

construction quality and

setting out of sewers.

More inspection

chambers and rodding

eyes.

Steeper falls and

increased pumping.

Consider low-flush

toilets.

Low-cost, small-bore,

shallow, and solids-free

sewers (with interceptor chambers) all work

better with lower water

availability than

conventional systems.

Consider decentralized

wastewater systems.

Consider grey water recycling for toilet

flushing.

If no water available,

sewers will not be a

Adapt maintenance

programme to reduce

blockages and increase

flushing.

If low flows available,

investigate alternative

methods to flush out or

maintain sewers.

Local management of

shallow and low-cost

sewers.

Improve solid waste

management especially

for fat solids.

Monitor water

availability.

Monitor sewer performance for

blockages.

Educate people about

what is appropriate to be

flushed down toilets in

low flows. If necessary, advice may need to

include that paper cannot

be flushed down toilet.

Ensure that no waste

disposal units allowed in

sinks.


low-flush toilets.



viable option. Investigate

other systems for

management of human

excreta.

Less water availability. More concentrated

sewage at treatment

plant.

Adapt treatment

processes to be able to

cope with more concentrated sewage,

e.g. more stages.

Consider diluting flows

before treatment.

Design effluent

standards for the context.

Treatment processes that are appropriate may

change with drier

conditions, for example ponds or reed beds can

be used in dry

conditions.

Decentralized systems

can be managed more

responsively.

Plan for increased

operational expenditure

requirements, e.g. power.

Reduced flows in surface

water.

Decreased dilution

resulting in higher

pollution loads in downstream water

bodies.

Improve the treatment of

sewage before discharge

to receiving waters.

Adapt sewage discharge

infrastructure to be

Increase monitoring of

pollution.

Reconsider effluent

standards and adapt for

changes in potential dilution.



suitable for low flows.

Consider design of

downstream water

supplies to take account

of increased pollution loads.

Reduced water for

irrigation.

Increased wastewater

use, and use of polluted

receiving waters.

Design distribution

system for wastewater

and an appropriate level

of treatment.

Consider disposal during

wet season.

Establish an appropriate

pricing scheme.

Health surveillance and

food quality monitoring.


awareness of possible

contamination of water

resources.

Changing moisture

levels in soils.

Movement and

infrastructure damage.

Design for movement,

e.g. shorter lengths of

pipes; or use non-reticulated systems on

site.

Adapt maintenance

programme to identify

breakages.

Monitor sewer

performance for

blockages and breaks.

Septic tanks




flushing and cleaning.

Toilet and discharge pipe

becomes dirty or

blocked.

Examine lower-water

use approaches (plastic

seals rather than water seals, for example) and

slabs that are easier to

clean.

Increase attention to

construction quality and setting out of sewers.

Consider feasibility of

households doing more

regular cleaning, rodding etc.

Improve solid waste

management, especially

for fat solids.

Septic tank system

inspections.

Education and awareness

of lower-water use

latrine options.


what is appropriate to be

flushed down toilets in

low flows. If necessary,

advice may need to include that paper cannot



More rodding eyes.

Steeper falls.

Consider low-flush

toilets.

If no water available,

septic tanks will not be a viable option. Investigate

other systems for

management of human

excreta.

be flushed down toilet.

Ensure that no waste

disposal units allowed in

sinks.


low-flush toilets.

Increased distance to

groundwater tables

Reduced risk of

groundwater pollution

Septic tanks become

more viable option

Changing moisture

levels in soils

Movement and

infrastructure damage

Design for movement. Adapt maintenance

programme to identify

breakages.

Monitor performance for

blockages and breaks.





flushing and cleaning.

Toilets become dirty or

blocked.

Examine lower-water

use approaches (plastic

seals rather than water seals for example) and

slabs that are easier to

clean.

Consider feasibility of

households doing more

regular cleaning.

Latrine inspections. Education and awareness

of lower-water use

latrine options.

Minimum standards for

slab construction.

Increased distance to

groundwater tables.

Reduced risk of

groundwater pollution.

Pit latrines become more

viable option.

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