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Jigabha, J.

~ Water metering development In Dar es Salaam,Tanzania

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Tampere, Finland 1992

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1. Jt may not be referredloastheofficlal~lEnaine~rinci, Tampere University of

Tampereen teknillinen korkeakouluVesi- ja ympäristötekniikan laitos

Tampere University of TechnologyInstitute of Waterand Environmental Engineering

No. B 52

Jigabha, J.

Water metering development in Dar es Salaam,Tanzania

LI~RARY,INTERNATIONAL REFEPE~!CEE~ ~OMMUN1TYWATER SUF~LY

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UDK 628.17 + 681 .1 21ISBN 951-721-866-4

Tampere, Finland 1992 ISSN 0784-655X

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1

WATERMETERING DEVELOPMENT IN DAR ES SALAAM, TANZANIA

by Jigabha Julius

PageTABLE OF CONTENTS 1

ABSTRACT 3

INTRODUCTION 41 . 1 Background of water metering 41.2 Objectives of the study 6

2 ASPECTS OF WATERMETERING 82.1 Water meter types 8

2.1.1 Positive or displacement meters 82.1.2 Inferential or turbine meters 92.1.3 Compound meters 10

2.2 Meter sizing, selection, installation andtesting 112.2.1 Meter sizing and selection 112.2.2 Meter installation 122.2.3 Meter testing 15

2.3 Methods of controlling unaccounted-for waterin the distribution system 162.3.1 Effective cost recovery policy 172.3.2 Provision of incentives and staff

motivation 182.3.3 Leakage control 182.3.4 Corrosion control 212.3.5 Maintenance and replacement of meters 22

3 STUDY METhODOLOGY 243.1 Selection of meters 243.2 Selection of sites 243.3 Data collection 25

4 WATERMETERINGPRACTISE IN DAN ES SALAAII 274.1 Control of unaccounted-for water in the

distribution system 274.2 Practices in planning and management of

metering 294.3 Consumer knowledge, attitudes and practices 32

4.3.1 Willingness to join and willingnessto pay 35

4.4 Effectiveness of water metering 364.4.1 Impacts of water metering 364.4.2 Tariff structure 384.4.3 Revenue collection 394.4.4 Joint water and waste water billing 41

4.5 Practices in operation, maintenance andreplacement of meters 41

5 METER INSTALLATION AND DATA COLLECTION 445.1 Meter installation 445.2 Data collection 49

2

6 ANALYSIS AND DISCUSSION OF RESULTS 52

7 CONCLUSIONSAND RECOMMENDATIONS 60

8 REFERENCES 63

APPENDICES 65

3

Jigabha, J., 1992.Water metering development in Dar es Salaam, Tanzania.Tampere University of Technology, Institute of Water andEnvironmental Engineering. Publication B52. 73 p.

ABSTRACT

The study aimed at developing water metering in Dar esSalaam. The specific objectives included the assessment ofthe acceptability of water meters, identifying watermetering problems, assessing the competence of developingcountries to cope up with the fast development of themetering industry and establishing features of an appro-priate water meter for developing countries. A literaturereview was conducted and a checklist of questions wasused in an interview of both the customers and the waterutility. In addition, a comparative field study onselected existing water meters and a prototype meter wascarried out.

It was revealed that lack of cost recovery is the biggestproblem. Water meters are used partly by selectedconsumers to establish defendable charges as an input toestablish tariff structures. It is recommended thatwater meters should first be introduced to big consumersand later to small consumers if the capacity to managethem increases. Further, regular evaluations should beconducted to assess the water meter utilization, forimproved water conservation and expanded service capacity.

The water authority has failed to recover a big amount ofmoney from its debtors. Small consumers especially inareas with intermittent water supply do not like watermeters, because they register air to a great extent.

Established programs of operation, maintenance, andreplacement of meters are not followed. Poor water qualitynecessitates regular maintenance of meters. The studyshows the extent of water quality effects on the meterperformance.

The field study was limited to turbine meters existing inthe distribution system. These were compared with proto-type meters. Piston type water meters require better waterquality compared to turbine meters. This feature hashastened their disappearance in the local systems leavingturbine meters in use.

Single-jet, dry dial turbine meters proved in principle tobe the most suitable meter type for Dar es Salaam network,provided that they have adequate protection againstexternal disturbance (vandalism, manipulation of readingsetc.) and have adequately high counting threshold to avoidair registration.

4

1 INTRODUCTION

1 .1 Background of water metering

Development of water metering in Dar es Salaam urban watersupply is receiving much attention after being employedsuccessfully in large scale programs for estimating con-sumer demand and analysis of water loss in distributionsystem. Through experience it has been evident that watermeters can be constant sources of revenue loss throughpoor management of operation and maintenance. Watermeters should perform efficiently if expected results ofmetering are to be obtained.

Van der Zwan (1988) pointed out that for correctestimation of water consumption in dwellings, domesticpoint or public stand post, water meters should beutilized. If water meters are properly utilized, the

- following is possible:

1) Detection of leakages in the water supply networkupstream the water meters. This method enablescomparison of total quantity of water supplied to thenetwork by employing master meters with theconsumption of individual water meters.

2) Detection of illegal connections, if leakage iscontrolled by the use of district meters.

3) Intervention and protection of wastage of water withinconsumer premises. This is possible if the consumer isaware that water actually consumed economically andwasted will be paid for.

4) Introduction of tariff systems based on the quantityof water supplied.

5) Utilization of saved water to enlarge the service areawithout necessarily increasing the productioncapacity.

Water metering in Tanzania is not a recently introducedpolicy. Like many other programs it has been practisedaccording to previous approaches as inherited from Englishcolonial masters. Despite long history and experiencegained, the use of water metering in Tanzania is stillmostly limited to urban water supplies. Among manyreasons, these could be ranked to be the basic ones:

a) Majority of water supplies are managed by the govern-ment, ministry or departments. Decisions are madecentrally and implemented at regional or districtlevel. The implementation level lacks authority to &

control daily activities.

b) The policy has been that in rural areas individualconnections have been discouraged (Katko 1989). Somegovernments favor the idea of providing free water to

5

the rural community assuming that consumers cannotafford to pay for water services. Establishing andmaintaining a metering system requires substantialforeign investment, which would otherwise overburdenthe already poor if they have to pay for waterservices.

c) Technologies used in most of the rural water schemesdo not influence the use of water meters. For exampleit is not economical to use meters for rural watersupply using hand pump technology.

In cities where water metering has a long history, theproblems existing are still out of reach of many waterutilities.

The following are the problems encountered:

1) intermittent water supply2) lack of continuous metering and control of water

supply networks3) poor water quality4) lack of trained manpower for operation and maintenance5) dependence of importation of spare parts and replace-

ment metres6) lack of equipment and transport7) lack of decision making and autonomy for setting local

water charges8) failure to collect revenue.

Bhattacharya (1982) outlined non-quantifiable auxiliarybenefits which are not evaluated by developing countries,but are of great importance in determining the servicelevel of a distribution system:

1) Meter reading helps to understand consumers’ wateruse patterns. This is necessary to forecast futuregrowth of water demand.

2) Meter reading at established or scheduled intervalsserves as a reminder that water has a cost. Thecustomer is compelled to use water more economically.

3) Reduction in use as a direct impact of metering maygive rise to surplus capacity of an existing watersupply system. Supply may be redistributed to increasethe service level.

4) Data keeping may be enhanced by metering. Such dataare daily per capital consumption, percentage of popu-lation served, per capita cost of water supply, etc.

6

1.2 Objectives of the study

To sustain a water metering system the following aspects

are important:

1) appropriateness of the meters in use2) management practices - operation and maintenance3) attitude of the customers towards the use of water

meters4) political influences.

Importance of evaluation emerges to reflect how thesystem is behaving compared to established objectives. Theprimary objective of this study was to look into theperformance of water meters in Dar es Salaam water supplydistribution network, so that the results may be utilizedby interest groups and users striving to balance capitaloutlays and revenues.

The study had the following specific objectives:

1) to assess the acceptability of water meteringpractices as a guide to establish undisputablecharging units for supplied water

2) to define specific water metering problems associatedwith current development of water meter designssuiting industrialized countries

3) to assess the competence of developing countries tocope up with development trends of the water meterindustry

4) to establish features necessary to develop an appro-priate type of a water meter for developing countries.

To achieve the above objectives, the study covered thefollowing:

a) Functional evaluation

This covered the performance evaluation of existing watermeters. Review of the practices in sizing, selection,installation, replacement, operation and maintenance.Further, analysis to determine functional problems ofwater meters was conducted.

b) Assessment of management effects on metering practices

This covered: &

1) planning and demand forecast2) consumers knowledge, attitudes and practices3) management practices.

7

c) Field study

1) defining operational problems, readability, relia-bility of data recording in direct meter readingsystem, detection of theft of water, etc.

2) suitability of the meter in local conditions, e.g.high temperatures, humidity, fluctuations in pressurelevels, etc.

3) effects of water quality on water meter performance

4) effects on water supply status e.g. intermittent watersupply and continuous water supply.

8

2 ASPECTS OF WATER METERING

2.1 Water meter types

Water meters are designed to provide, without the need forcalculations or any manipulative skill, direct informationregarding the quantity of water flowing through thepipeline. The volume of water can be indicated by pointersmoving over dials, by counters or recorded automaticallyon a chart. Attachments for automatic remote transmissionof readings may be provided.

Water meters can be categorized based on quantity (totalflow or volume) and rate of flow. The quantity meters arethose which indicate in units of volume the quantity ofliquid that has passed through the pipe in the intervalbetween two successive readings. The rate of flow metersindicate the discharge along the pipe in units of volumeper time. The former category is the one used in the waterdistribution system.

Quantity meters are divided into two main groups: positiveor displacement meters and inferential or turbine meters.One sub-group used is a combination of the two meters inparallel to form compound meters. It is also possible tocategorize meters according to their use. Actually theyfall almost under the same groups as may be seen later.

2.1 .1 Positive or displacement meters

Positive meters are those in which the recording of thetotal flow is based on counting the number of times thatmeasuring chambers of known volume are successively filledand emptied. Because of this phenomenon they are sometimescalled volumetric meters.

Measuring chamber or set of chambers is the basic elementof a positive meter. Several designs have been developedand used in the field of water supply. Such designs aredisc meters (Figure 1) and oscillating piston meters(Figure 2). Close fit between the moving parts in themeasuring chambers is the governing factor for accuracy ofthe meter. Of these parts, the cylinder (chamber) is themost desirable, because it enables some kind of seal orparking to be provided between piston or disc and thewalls of the chamber. Modern displacement meters havecapillary seals rather than packing seals to preventslipping which might impair low flow accuracy (AWWA1986 a).

9

To Registe~in1çDials _______

SECTION

~D/sc

if~~-. 50 135~ 18O~

SECTIONS XX AFTERSUCCESSIVEMOVEMENTS 0p45O

Figure 1. Disc meter (Kent Meters Limited 1988).

Partition -

Figure 2. Oscillating piston meter (Kent Meters Limited1988).

2.1.2 Inferential or turbine meters

Turbine meters are sometimes referred as propeller typemeters. The measuring element is a rotor or propellerfacing upstream (Figure 3), which is rotated by thevelocity of water striking its angular blade. Based on itssimple operation the inferential meter is regarded as aminiature hydraulic turbine working under no load.Especially in large sizes the propeller may be smaller in

10

diameter comparing to the internal diameter of the pipe.This is intended for the main line services were flowrates do not change abruptly, as the propeller has aslight lag in starting and stopping.

U

Figure 3. Propeller meter (AWWA 1986 a).

Various methods of transmitting motion from the propellerto the register unit have been developed, e.g. magneticdrive, gear train drive, etc. The magnetic driveeliminates the gear trains from the main casing and uses amagnetic unit to transfer the motion to the register. Themain achievement in this design is that the register issealed against air and moisture. The inclusion of theregister with its high impact resistance lens reduces bothfogging and breakage of the lens, and corrosion of theworking parts. The conversional gear train transmissioncan be run dry or wet. This had been used to sub-dividethe meter into wet or dry type. The wet type has itsworking parts submerged into the water to be measured. Incase of turbid water this type of a meter can be easilyclogged.

2.1.3 Compound meters

A compound meter includes a meter of large capacityplaced in the main service line to register larger flowsand a smaller by pass meter to measure small flows.Automatic valves are also included for diverting the smallflows to the by-pass (Steel and McGhee 1979).

Compound meters are basically turbine meters meantlarge flows to industries and commercial areas.inability of these meters to detect small flows belowof their normal discharge can be remedied by usingsmall and one big meter in parallel (Figure 4).arrangement necessitates the reading of two dials andarithmetic addition of the two registrations givestotal quantity of water passed through the pipeline.

‘~-ff

forThe

1/20one

Thisthethe

11

Figure 4. Compound meter (Smith-Vargo 1989).

2.2 Meter sizing, selection, installation and testing

The binding of the meter turbine, disc or piston usuallyrenders high capacity meters placed in low use serviceline unserviceable. Such cases are common where overcapacity meters are installed, either upon insistence ofthe customer as he/she wishes to ensure receipt ofsufficient pressure and flow or due to over design.Failure of these meters to operate properly will result toincreased non-revenue water and maintenance costs due tostopped meters. On the other hand, undersized meters willcause customer complaints, excessive wear on the meter,high maintenance costs and poor publicity of the waterutility. Such incidence may be avoided by followingestablished criteria for sizing, selection, installationand testing.

2.2.1 Meter sizing and selection

The selection of water meters involves both size and typeof meter. The selection of meter size does not meanmatching with the pipe size. The pipe is usually oversizedto allow possible future increase in water demand or justto reduce pressure losses in a long pipe. According toAWWA (1986 b), the type of the meter is determined by therange of flow rates, plus allowable pressure losses andpossibly inclusion of safety requirements, e.g. fireservice regulations, etc.

The flow rates are classified as small flows, medium flowsand large flows. Most residential services are small flowsmetered with 16 mm (5/8”) size having 20 mm (3/4”)connections. Various manuals have been developed and usedby design engineers. JICA (1991 a) recommends the meterselection based on planned maximum daily demand (Table 1).

12

Table 1. Selection of types of meter (JICA 1991 a).

Size

mm (inch)

Meter type Maximumdemandm3/d

daily Regulamaximm3/h

tedurn flow

13 (1/2) straight line,inferential 6 1

20 (3/4) dual—pipe,inferential 12 2

25 (1) dual—pipe,inferential 15 2

40 (1 5/8) vertical,axial flow 48 8

50 (2) vertical,axial flow 120 25




Knowledge of data about the customer’s maximum probablewater demand is essential in meter sizing. The customer’sservice line from the meter to the building must beexamined to assesswhether or not it is adequate to supplythe peak demand. If the pipe is not of sufficient size,changes must be suggested. Otherwise the water utility maywish to refuse service pending installation of the propersize of pipe. AWWA (1986 b) recommendsthe system designto be based on provision of adequate pressure at theconsumer’s meter outlet during the period of highestdemand.

2.2.2 Meter installation

Poor installation may cause the meter to be under mud orground water, thereby creating difficulties in reading,replacement and maintenance. Water meter for customerservices are installed in two basic ways: indoor andoutdoor setting. In an indoor setting the meter isinstalled inside the customer’s premises, usually in thebasement. In an outdoor setting, the meter is installedunderground in a pit (Figures 5 and 6) or meter box whichis usually located under the curb end of the service line.According to Manson (1989) it is cheaper to installmeters indoor even if an out reader is used. They areeasier for the customers to read, less prone to vandalismand less problematic to common services, e.g. repair ofleaks and replacement. Outdoor installations arerelatively free of access problems, a distinct advantagewhen it comes to reading and maintenance.

13

Albro (1985) concluded the following features to depict agood meter setting:

— protection against environmental hazards, particularlyfreezing, excessive heat and vandalism

— convenience for reading

— easy accessibility for maintenance and replacement

- should not be unobtrusive as possiblehazards to pedestrians or to customers.

and offer no

Figure 5. Outdoor meter setting with integral yoke (AWWA1986 a).

Figure 6. Outdoor meter setting with meter yoke1986 a).

(AWWA

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There are advantages and disadvantages resulting from thetwo settings. Advantages of outdoor setting are (Albro1985 and Brainard 1985):

— The meter is always accessible. There is no need forentering the customer’s premises for inspection,reading and replacement.

- Since meter box lid can usually be locked, only utilitypersonnel have access to the meter, hence safe againstvandalism.

*

- Reducedin-house hazards, e.g. fire.

Disadvantage of outdoor setting may be summarized as(Albro 1985 and Brainard 1985):

— High costs for protection against hazards, e.g. frostduring winter, storm run—off, etc.

- If box lids are not properly secured, pedestrians canstep into the open pit resulting liability problems forthe utility.

For the indoor setting, the main advantagesare:

— excellent protection against cold weather during

winter (Aibro 1985)

- lower installation costs (Aibro 1985)

— reduced damage and maintenance costs due to elimination

of exposure to outdoor conditions (AWWA 1986 a).

Disadvantages include (Albro 1985):

- The meter setting is not completely under control ofthe utility, therefore prone to high risks of vandalismand tempering.

— Missed readings due to entry problems.

- Unregistered service line leaks can take place betweenthe main and the house. There is always a question ofwhose responsibility it is to repair leaks.

Large meters are used where high flows of water arerequired. With large water meters there is a potentialrevenue in jeopardy if it does not register properly.Assuming that an accurate, carefully selected large meteris to be installed, it is worth to observe water meterdesign parameters that affect installations. AWWA(1986 a)noticed large water meters installed horizontally, towork best when there is a swirl free, uniform flowvelocity profile in the pipe immediately upstreamof themeter.

15

Brainard (1985) recommendedthe following for optimum lifeand best accuracy of large turbine meters:

- Piping upstreamof the meter should be straight and tostandard as per meter manufacturer’s specification tominimize the flow disturbances in the meter.

- Piping downstream the meter may disturb the flowupstream of the meter. Therefore no fittings that willcause low disturbances should be bolted directly to themeter’s outlet flange.

- Shut-off valve should be provided for isolation of anymeter installation, because eventually maintenance willbe required.

- Control valves of any form should be installed upstreamof the meter regardless of the piping separation.

- Strainers upstream the meter are essential to protectthe device against possible damagesand also to assistin correcting upstream flow disturbances.

— By—pass around the meter is necessary if water servicesMust be maintained at all times.

— Periodic accuracy testing is important for large watermeters than for positive displacement, because therevenue loss through an inaccurate large meter canrepresent a considerable amount.

— Flexible couplings are recommendedto prevent problemsof dismantling and settling of pipe after a period oftime.

2.2.3 Meter testing

Meter testing may be carried out in a workshop or in thefield. Meters should be tested to protect the customeragainst meter inaccuracy that result to overcharges.Conversely, the water utility looses revenue if meterinaccuracy results to undercharges. The method used todetermine the optimum number of years a meter shouldremain in service between tests, is to test 5 % of metersscheduled for next periodic testing under an existingtesting program. AWWA (1986 a) suggested that if theresults of the tests fall within the accuracy shown inTable 2, it can be assumed that the remaining meters wouldproduce the same average test results.

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Table 2. Required accuracy limits for compliance withguidelines (AWWA 1986 a).

Meter type(all sizes)

Accuracy limits as found by test

Normal testflow rates%

Minimum testflow rates%

Displacement 96 — 102 80 — 102

Multi—jet 96 — 102 80 — 104

Propeller andturbine 96 - 103 not applicable

Compound andfire service 95 - 104 not applicable

All new meters should be tested for accuracy ofregistration at low rates and test flow quantities, inaccordance with manufacturers recommendations before theyare put in service. Further a program of periodic testingshould be established. It is advisable to provide morefrequent tests for large meters, because an error in theirregistration affects revenue to a much greater extent. Thecost effective time to replace a meter in the system isrevealed only in an on-going meter testing program.

Field testing is essentially the same as workshop testing,except that instead of using a tank for the test water, acomparison is made between the meter to be tested and onethat has been previously calibrated. Field testing is usedfor convenience, and especially for meters which requirelarge quantities of water and if facilities at the shopare not adequate. AWWA(1986 a) advised to field test allsizes of compound meters and those larger than 50 mm.

2.3 Methods of controlling unaccounted-for water in thedistribution system

Unaccounted-for water (UFW), also known as non-revenuewater (NRW), was defined by Jeffcoate and Saravanapavan(1987), as the difference between the water delivered intothe distribution system and the volume of water consumedthat can be accounted for, whether metered or not metered.This definition may be expressed in formula form as:

UFW = T - (M + uP)

where, T = total water suppliedM = metered consumptionu = unmetered per capita consumption based

estimateP = population served.

U

I

(1)

A

on

This may be expressed in percentage form as UFW/T100 %.

17

There are several methods developed in practice that areused for controlling non—revenuewater in distributionsystems. The reasons for non—revenue water are many andalmost continuous requiring a definite policy for theircontrol. In practice there is no system withoutunaccounted-for water. Low and high percentages of UFW indistribution systems are used to distinguish betweenefficient and poorly managed systems. In pursuit of thecontrol policy, strategies are established to contain themagnitude of UFW within acceptable limits. The strategiesshould cover but not be limited to effective cost recov-ery policy, provision of incentives and staff motivation,leakage control, corrosion control, maintenance and re-placement of facilities.

2.3.1 Effective cost recovery policy

The cost recovery policy should stipulate mechanismsnecessary to mobilize input resources in order to maintainthe services. Such mechanisms if introduced andadministered correctly should lead to more efficientoperations of development projects. Developing countriesare not yet fully committed to the “user pays principle”applicable in developing countries.

When citing Rimer and Associates 1970, Katko (1991) gavean example of Eastern African countries. Since achievingindependence, these countries adopted the policy of sup-plying water totally or, almost, free of charge to ruraland urban fringe consumers. In Tanzania for example, ittook more than two decades to realize that this policy isnot sustainable. In 1965 the government of Tanzania tookover the investment costs and in 1970 the operation andmaintenance costs were also taken over (Katko 1989).Absence of an effective cost recovery policy acts as adisincentive to proper use of facilities and resources,because the subsidies provided by the government tend tolead to dependency. To create independency cost recoverymeasures must be adopted and utilized. If financial subsi-dies are to be provided they should be justified.

Water authorities employing the “user pays principle” arerequired to consider economic efficiency in theformulation of pricing structures and determination oftariff levels. They should also consider environmental andconservation objectives, need to raise sufficient revenueto cover costs and creation of equity (United Nations1981, cited by Katko 1989). Katko (1989), noted theconcept of equity or fairness to be complex,and urged that it must be approacheddifferently depending on situations. He, however, stressedthe need for developing countries not to provide thebasic need consumption free, but rather at a fairly lowrate. The bigger consumers should be charged at a higherrate per volume consumed.

Revenue raised by water utilities must cover operation,maintenance and investment costs. In Dar es Salaam othercosts such as current depreciation as well as earning theopportunity cost of the public sector capital are beingconsidered in recent inflation accounting (SAT 1991).

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2.3.2 Provision of incentives and staff motivation

Limited financial resources in developing countries hascaused most of the water authorities to oversee the needfor provision of incentives and motivation of their staff.Control of UFW is a continuous process requiringinvestment in human and financial resources. In developingcountries where manual operations are still widely used,employees need incentives to approach their task withenthusiasm. The most valuable approach is the day to daymaintenance, which can be effectively accomplished bymotivated staff. Public recognition works equallyeffective as financial rewards. Each aspect works betterwhen employed in its right place at the right time.

Training of staff may be employed in a motivation package.The fact that facilities for operation and maintenance areused by few who are skilled, training of additional peoplewill motivate them. Acquisition of such a knowledge maylift one up to a better working environment. Some may havepicked up the knowledge gradually and use such facilitiesineffectively. The management should pay interest toimprove their skills. If selected carefully, only a fewpersons can play a key role in organizing the intensifiedtraining of additional operators.

Use of latest technology in modern water undertakings, hasaltered the status of engineers and technicians engaged inwater supply so that they are now key employees. ~This isrecognized as an incentive to effective managements andcontrol, unfortunately unknown in many developingcountries. Jeffcoate and Pond (1989) proposed that latestemerging technologies and proposed installation indeveloping countries should be planned to overcomepossible operational problems. The immediate plans,however, must always be to improve things slowly wherethat seems possible.

2.3.3 Leakage control

Leakage control is feasible when the entire supply networkis monitored and pressure controlled. It is indeed anexpensive undertaking, requiring effective tools andequipment besides skilled personnel. Usually an estimatedamount of UFW should be known in order to detect andfinally locate leaks. Whenever the estimated allowablevalue is exceeded it is recommended to conduct anappropriate leakage control measure. According to Bays(1984) the following methods are used in leakage control:

- passive control- regular sounding- district metering— waste metering- combined district and waste metering- pressure control.

19

Passive control is used without the need to measure ordetect leaks. Leaks are repaired when reported either bythe public or the utility personnel engaged in othertasks. The reporting can be through goodwill if the publicnotices visible leaks, or through complaints of no waterflow or low pressure. In most cases the invisible leaksmay cause a considerable water loss.

Invisible leaks are difficult to detect, requiringspecial equipment and skills. They may be through valves,service connections or pipe busts. In this case thesounding technic used by trained inspectors is employed bysystematically working around the distribution system. Thetechnic requires listening and distinguishing thecharacteristic noise of leaking water. According to Bays(1984), regular sounding is relatively inexpensive method,and therefore most effective in areas where the value ofsaving water is fairly low.

In district metering the supply zone is sub-divided intosmall convenient districts and the flow to each districtis permanently supplied with water through a metered line.The meters installed at strategic points should be read atregular intervals. Jeffcoate and Saravanapavan (1987)cautioned that the districts may be completely isolatedexcept for the meter entry points. By selecting the areaswhere the leaks are likely, the authority may wish toinclude as many properties as practicable. The normalrange is between 5 000 to 10 000 properties (Bays 1984).This method is accompanied by a disadvantage, thatselecting leaking districts would make the highconsumption become the normal figure for that district.The strategy used to curb this, is to convert the meteredflow into liters per property per hour say for a day, andbasing on the district with high figures the investigationis conducted immediately. It is worth to note thatdistrict metering is not sensitive to increased leakage,neither does it determine the position of the leaks veryclosely (Bays 1984).

Waste metering has the merit of detecting the occurrenceof small leaks. Bays (1984) recommended this method to beapplied in areas where the value of water saving is veryhigh. This is because much time may be spent in areaswhere no leakage has occurred since the last test. This isan expensive undertaking which must be justified onlyafter considering the cost-benefit of the exercise. Themethod involves dividing the district into smaller areas.By test isolation, the flows to all these areas of thesystem can be checked regularly and any unaccountablechanges investigated. Jeffcoate and Pond (1989)recommended 1 000 properties in these areas. When thecorrect valves are closed, the area can be supplied by asingle main in which a waste meter can be installedcapable of measuring low rates of flow.

Measureflient of night flow rates helps to identify possi-ble leakages in the system. In this respect the wastemeter either installed on a bypass or mounted on a mobiletruck, may be used by connecting it to the main by means

20

of hydrants. The recording type meter is left in operationwhen the normal flow has ceased say at midnight, to recordminimum flows. If there has been significant increases inflow from previous test in the same district, then furtherinvestigation should be conducted. By stepwise shuttingthe valves in the entire waste district, the point ofleakage can be pinpointed to a particularly small sectionfor sounding and location. Bays (1984) recommended to takemeasurements at least twice a year or even more frequent-ly. A combination of waste and district metering is anoth-er possible method.

Pressure control ensures the system against thepossibility of surges in the pipe line. Especially whereintermittent water supplies are experienced, the pressuresurges are difficult to prevent. There is evidence thatwhere high pressures exist, the probability of havingleaks and bursts is higher. Jeffcoate and Saravanapavan(1987) identified the phenomenon where the pressure-flowrelationship did not follow formulas established. Insteadthe relationship formed a curve (Figure 7). The phenomenonwas attributed to the tendency of orifice size to increasewith pressure. This explains why the leakage increaseswith pressure.

Pressure reduction as a method of leakage control, shouldbe carried out carefully because it might have a negativeeffect on service level (Bays 1984). Pressure reductionmay be accomplished by the following methods:

1) maintaining desired pressure level on the downstreamside by installing automatic pressure regulatingvalves

2) use of break pressure tanks

3) by dividing the supply area into pressure zones

4) reinforcing the network to minimize friction losses

and permit operations with reduced working pressure

5) introducing pump speed control or other means ofreducing night flows.

21

wV

a)01

a)

Figure 7. Typical relationship between leakage andpressure (Jeffcoate and Saravanapavan 1987).

2.3.4 Corrosion control

Corrosion of pipes and accessories can be a major sourceof water leakage in the system. Especially in highpressure zones,new pipes and accessories must be protectedagainst possible corrosion. O’Day et al (1986) remarkedthat it is not economically feasible to protect old pipes,unless those with significant remaining life in areas ofhighly corrosive condition. Unfortunately the pipelinesare normally buried some meters below the ground, whichrequires higher replacement and maintenance costs.

Corrosion of pipes happens either internally or external-ly. If the pipes (especially iron and steel) are notinternally lined with anticorrosive material, the thick-ness of wall js gradually lost by corrosion. The internalwall of the pipes which are not homogeneous will create acorrosion cell with water in contact. The external corro-

Average zone night pressure (m)

22

~ion of pipes results after the pipe-soil corrosion cellhas been formed. The extent of corrosion depends upon theresistivity of the soil which is affected by the soil typeand the moisture content of the soil (O’Day et al 1986).

Protection of pipe corrosion in practice is trying tolimit the formation of the corrosion cell around thesurface of the pipe. For internal protection, nonmetallicmaterials have been used extensively, e.g. cement lining.Another method used is the application of corrosioninhibitors to the water prior to distribution. O’Day et al(1986) enumerated commonly used inhibitors to be: phos-phates, silicates, calcium hydroxide, sodium hydroxide,sodium carbonate and sodium bicarbonate. Externalcorrosion are protected by: control of galvanic andimpressed electrolysis, cathode protection, polyethylenewrap and the use of plastic and epoxy coatings. Poly-ethylene has been used to provide a barrier between thepipe and the soil. Plastic and epoxy coatings have beenutilized in much higher corrosive areas.

2.3.5 Maintenance and replacement of meters

To maintain an effective water metering system a compre-hensive maintenance and replacement program should be pre—planned and effectively implemented. Like many otherfacilities, water meters require repair for maintenancesoon after installation. There can be a variety of reasonsranging from vandalism, accidents, natural disasters topoor water quality especially in developing countries.

Operational or new meters need to be in stock forimmediate replacement of malfunctioning meters ifconsistent metering is to be ensured. To carry out acontinued maintenance program, means of communication,transport, recording and spare parts should be constantlyavailable. Standardization and minimizing variety of watermeter brands in the system is an important prerequisite ina smooth operation and maintenance program. This limitsthe training expenses required for the meter repairers tomaster each brand in the network.

After laying and maintaining pipes, pipelines must bethoroughly flushed through before fitting a meter. Thereis a possibility to have foreign matter in the pipelinewhich may easily clog the meter. Various materials havebeen recovered ranging from small animals to pieces ofcloth. For this purpose, a blank of the same length as themeter is fitted into the pipeline instead of the meter.After the piping has been flushed, the meter can be fittedin its place. To prevent the consumer from fraudulentlyreversing the meter from time to time, thus making it runbackwards and in this way drawing unpaid water, the unionupstream the meter can be lead sealed. Where there is aneed to maintain service, as to a hospital, commercial orprocessing industry, a temporary or permanent bypassaround the meter is installed (AWWA 1986 a).

23

Water meter replacement is immediately required once themeter is removed. The urgency of replacement depends onthe importance of the service line. Some lines requirecontinuous water supply, for example in hospitals andproduction lines. In such cases bypass pipes and metersmust be provided to ensure continued supply and registra-tion of water supplied (Figure 8).

OPTIONAL THROTTLING VALVE,CHECK VALVE. BACKFLOWPREVENTOR OR PRESSURE-REGULATOR

DOWNSTREAM-SHUT-OFFOR ISOLATION VALVEFULL OPENING

DIRECTION OF ].._-5 PIPE DIAMETERS—..] STRAINER MINIMUM OF______ AND 5 PIPE DIAMETERSWATER FLOW TURBINE METER DOWNSTREAM OF

~— TURBINE METER—TEE SERVICEOR PIPE PLUG

Figure 8. Meter installation with a by-pass pipe (AWWA1986 a).

In developing countries problems ranging from inadequatefinancial resources to shortage of material and spareparts have resulted in a rate of implementation far belowplanned targets. UNDP and the World Bank (1990) identifiedmajor unresolved water supply and sanitation issuescausing such problems in Tanzania to include:

- unclear and overlapping institutional responsibilities

— insufficient coordination of donor activities resultingin projects and programs with different objectives andapproaches

— lack of firm and clear investment, financial andimplementation policies and strategies.

24

3 STUDY METHODOLOGY

The study comprised two main activities:

1. evaluation of water meters in use, based on availableliterature and information gathered throughquestionnaires prepared and used in interviews

2. field investigation on selected reference metersworking in series with the prototype meter.

4

In evaluating the water meters in use, practices insizing, selection, installation, operation and maintenanceand replacement of meters were assessed.

3.1 Selection of meters

The assessment of sizing and selection was conductedthrough interviews to NUWA (National Urban WaterAuthority) personnel, because the meters selected werealready existing in the network.

The target meters selected were those employed in thedistribution network. It was not convenient to collect allavailable water meter types and brands to accomplish thestudy. The selection was limited to Dar es Salaam andTanga water supply networks because of time and humanresources limitations. The water utility and customers inTanga were known to complain about the suitability of themeters used in the water supply network. This paid aspecial interest to investigate how the same meters wouldbehave in other environment like Dar es Salaam.

The target meters in Dar es Salaam were those metersexisting in the distribution system. After earmarking theinstallation sites, all meters existing were taken forrecalibration. Each target meter was connected in serieswith the prototype meter.

The prototype meter originally manufactured by Valmet inFinland is no longer in production (Mäntylä 1991). Theworking machinery of this meter is not manufactured bymodern cheap plastic materials. According to Mäntylä, itis reliable, less sensitive to air flow, less sensitive tosmall flows and more durable to turbid and aggressivewater. This rose interest to have it tested in series withthe existing meters.

3.2 Selection of sites

To undertake field investigation, selected sample metersand prototype meters were installed in six strategiczones selected with the help of NUWApersonnel. Problemsthat occurred in practice were recorded and compared withthose obtained during interviews. In order to get enoughdata, a weekly reading system was introduced.

25

The field study was conducted in Dar es Salaam, thelargest city in Tanzania with a population ofapproximately 1 360 000 according to 1988 census. Dar esSalaam city has got the oldest history of water supply inTanzania, being established in 1891 (JICA 1991 a). Thewater meters are known to have been used since the early1950s. The water supply inherited after independence in1961 contained mainly water meters manufactured inEngland, the last colony master. Hitherto various brandsof water meters from different countries are found indifferent water supply networks. This depicts the range ofco-operation the country selected to pursue inimplementing its metering policy.

3.3 Data collection

Information and data were collected from literature andthrough interviews. In literature review currentpublications e.g. journals, books, seminar/conferencepapers, etc. were used. This supplemented the informationgathered from interviews.

The objectives of the interviews were to assess:

1) customers’ attitude, knowledge and practices towardswater meter utilization

2) acceptability of water meters among customers

3) necessity of water meters utilization in the watersupply network

4) management and planning practices in sustaining ametering policy

5) practices in sizing, selection, installation, replace-ment, operation and maintenance

6) effectiveness of water meter utilization.

Because of limited resources both in terms of time andmanpower, a statistical approach in carrying interviewswas not used, instead a checklist of questions wasprepared. The questions constituting the checklist wasdeveloped after consulting a sociologist. In the processof gathering more ideas to formulate an exhaustive check-list, testing was conducted to the Ministry of WaterEnergy and Minerals (MWEM) personnel. Interviews wereconducted by physically visiting the prospective re-spondents and asking questions following a check list.As the interviews continued, most of the questions weremodified depending on the respondent’s education level,social status, economic status, international orientation,etc.

26

The persons to be interviewed were selected based on thefollowing criteria:

1) big consumers of water and especially those who haveused water meters for a long time

2) those who show interest to view their opinions basedon their previous experience on meter utilization

3) customers whose service lines will be connected withtarget meters

4) customers who know the interviewer. This may eliminatethe possible doubts the respondent might have onintentions of the interview

5) customers and personnel in the water utility whom the

interviewer can contact easily

6) social status of the respondent

7) international orientation, e.g. expatriates working in

Tanzania.

To assess the operation and maintenance of the watermeters, the meter repairers and readers were involved inthe program of inspecting and reading meters once perweek. It was necessary to cross—check the data collectedby anonymously visiting the sites and collectinginformation. The method was deemed to establish the mainproblems of the metering system, highlighting the linkagebetween intended inputs, planned activities and expectedresults. The method enabled to analyze and define themetering problems, and alternative approaches. The inputdata mainly resulted from the questionnaires prepared andused in an in-depth study.

27

4 STATUS OF WATERMEri~RING IN DAN ES SAIIAAM

Collection of information regarding the status of watermetering in Dar es Salaam water supply distributionnetwork was two-fold: use of interview and review ofavailable literature in the Ministry of Water, Energy andMinerals (MWEM) and National Urban Water Authority (NUWA).The following two approaches for conducting interviewswere considered:

1) Preparation of questionnaires and distributing themto prospective respondents.

2) Preparation of a check list of questions andconducting interviews. The interviews were conductedby visiting the interviewee and asking questions basedon the check list. The check list was modified as theinterviews continued.

4.1 Control of unaccounted-for water in the distributionsystem

Water losses in the distribution system are mainly~ foundin house service pipes, valve seatings and public stand—posts. It is estimated that the domestic water consumptionis 57 % of the total water consumption. The totalproduction is 40.3 million gallons (183 000 m3) per day.According to JICA (1991 b), the losses were estimated tobe 25 % - 40 % of the flow in the system. Approximately14 million gallons per day (62 000 m3/d) is available fordomestic consumption. The following reasons were found tobe responsible for water lost and wasted (JICA 1991 a):

1) leakage from reservoirs, pipe mains, appurtenancesand service connections and wastage of water intreatment plants

2) unauthorized or unknown use, and wastage of waterthrough disuse or abandoned connections

3) inordinate consumption of water by consumers due toexcessive use of water for gardening, washingvehicles, floor, etc.

4) misuse of water for miscellaneous purposes

5) failure to turn off taps in premises, purposely orinadvertently

6) in intermittent supplies emptying of stored water ina receptacle, when fresh water arrives and, keepingthe tap open throughout, thus allowing water to gowaste

7) unduly high pressures in the distribution systemintensifying leakage and wastage

8) water which is legitimately used, but not properlyaccounted for, e.g. at public standpipes

9) errors in measurements at any stage of production,supply and distribution

28

The use of water meters to determine the water supplynetwork efficiency is no longer applied in Dar es Salaamwater supply. The method of district metering was appliedto detect and control leakages in Sinza area as a pilotproject (Mihambo 1992). In this pilot project, severalmetering districts were earmarked and the flow to eachdistrict was to be permanently supplied with water throughone or several meters. The meters were installed incarefully selected points and flow in the districtsmeasured. The meters were read weekly during day times andnight times, while noting significant changes. Inspectorsmade sounding of the fittings such as valves, stopcocks,etc. and listened for sounds of leaking water. Initialindicators of the project were promising. The leakageswere reduced from the initial 40 % in the area to 25 %.The improvement of this figure could be obtained if wastemetering was to be conducted effectively. The waste metercan be installed on a bypass or mounted on a mobile truckwhich can be connected to the mains by means of hydrantsand is used to measure night flows. The team lackedrecording meters usually put into operation when thenormal flow has ceased say at midnight. The meter is leftin place overnight and the minimum night flow can be readfrom the recorder. The project was abandoned followi’?’igfailure to obtain enough meters as per requirement(Mihambo 1992). Figure 9 shows the plan of the wastedistrict initially used.

Figure 9. Plan of district metering as designed and usedin Sinza area - Dar es Salaam (Mihambo 1992).

29

The current method used is passive control. In thismethod, only visible and reported leaks, or those found asa result of reported low pressure, no water supply or ofnoises in the internal system are repaired. This methodhas not been effective in reducing the UFW to acceptablelimit of 10 %. There may exist areas of high invisibleleaks that might not be identified by physical inspection.This method requires reliable transport which fails theexercise to a greater extent. Coupled with poor tools andold equipment only “first-aid” repairs can be attended.Table 3 shows reported against repaired leaks.

Table 3. Cases of leakage reported and repaired in Dar esSalaani water supply distribution system (SAT1 991).

Year Numberleaks

ofreported

Numberleaks

ofrepaired

1984/85 848 8071985/86 1 072 9911986/87 1 575 1 2991987/88 5 831 5 523

Continued monitoring requires substantial investments inhuman and financial resources. Modern computers enablecentrally monitored operations, which assist in managingoperations of large schemes. Limited financial resourceshave always forced developing countries to rely on manualoperations. This has limited the operational capacity andefficiency of many projects.

4.2 Practices in planning and management of metering

The outstanding obstacle in provision of sufficient waterservices in Tanzania is institutional weakness. Theproblem is that responsible authorities of differentprojects fail to quantify to extent possible, operationalindicators that can be used as corner marks duringexecution of projects. The governments of developingcountries ranked major constraints according to t4ieirsevereness as (Pineo and Subrahmanyam (1975), cited byKatko 1986):

- insufficient internal financing- lack of trained personnel- inappropriate administrative structure- lack of external finance- inappropriate financial framework- insufficient production of local material— inadequate or outmoded legal framework.

30

Lack of firm and clear investment policy may be consideredthe main problem in Dar es Salaam water supply. There isno clear benefit-cost analysis made to justify the watermetering investment. Surface water used in Dar es Salaam,is not effectively cleaned to ensure a constant quality.Usually sand and high variations in pressure add an extracost to the maintenance of meters.

Water supply in Dar es Salaam currently managed by NUWA,is not enjoyed by the entire city population. Theauthority was established in 1981 as a parastatalorganization to manage all urban water supply systems,taking over all activities from the Dar es Salaam WaterSupply Corporation Sole. The problem is to improve thewater supply to the city by considering the wider socialand physical features of the system. In Dar es Salaam, thepopulation and the urbanized areas have increased rapidlyin recent years. According to JICA (1991 b), the totalwater consumption in 1990 was 144 000 m3/d, of which,128 000 m3/d for domestic; 5 000 m3/d for industrial;6 000 m3/d for commercial and 5 000 m3/d for institu-tional. Apart from working against an increasingpopulation, it was noticed that water supply suffers fromthe following:

- heavy water loss through leakages, illegal connections,which results in vending and reselling

- insufficient utilization of existing water supplyfacilities, e.g. treatment plants, storage tanks, watermeters, etc.

— poor raw water quality

- insufficient water supply.

Lindh (1983) commented that when planning it is certainlydifficult to account for all the possibly dependentprocesses which take place in the urban water sphere.Untimely upgrading of facilities coupled with rapidurbanization have rendered the infrastructure servicesinadequate. In fact that does not prevent the plannerfrom proceeding systematically.

LikeS other projects in developing countries insufficientwater supply may be attributed to lack of sufficient costrecovery needed to contribute to the system expansion andmaintenance of existing facilities.

The history of water metering in Dar es Salaam is madeclear by looking at the pavements between buildingsusually where installed meters may be found. There can beseen a variety of water meters connected to almost everyservice line. Getting closer to the site reveals that themajority of them are not operational. Those meters whichare not working have been left in place to minimize thereplacement costs of meters, fittings and oftentimes pipesthat can be broken during connections or disconnections.

huom

31

This has resulted to unoperational meters being left inservice lines. This practice may be contributing tofriction losses in the system and sometimes unnecessaryblockings of the pipeline.

Apart from prohibitive costs of metering, low pressure inthe system has rendered water metering always impractical.Nevertheless, apart from these drawbacks NUWA maintainswater metering to at least big consumers. If NUWA foundwater metering totally not beneficial, it could have beenrejected. This shows that metering has had a great impacton consumers.

According to JICA (1991 a) universal water metering in Dares Salaam would not be feasible. The study conductedrevealed that selective metering of target customers is abetter solution. It is thought that this practice wouldresult in 10 % reduction in high consumption houseconnections. Metering is deemed for water conservation andrevenue increase. According to this study, metering highincome households would decrease per capita consumptionfrom 1 800 - 1 600 m3/d. With 15 000 high incomehouseholds metered, saved water will amount to1.2 million m3/a. By distributing this water to otherconsumers, a monetary gain of TZS 65 million per year willbe realized. This is an auxiliary achievement, whichaccording to Bhattacharya (1982), most of the developingcountries have always neglected to evaluate.

Water meters should be read once per month and billsprepared according to monthly consumption. The meterreaders are required to visit each meter to collectconsumption data and inspect them for possible repairneeds. Each meter reader is assigned one zone. Not allmeters are read or inspected according to schedule. Lackof transport was accused to be the major problem. Anotherproblem is lack of working tools and equipment to enablerepairs of water meters for immediate replacement. Aconsumer may deliberately break the meter so that he maybe billed on flat rate if the neighbor is said to pay lessbased on flat rate.

Some consumers may have water meters operational but notcharged according to the meter reading. The customersinterviewed revealed this to be attributable to poormanagement of the meter reading system. Most of thedomestic consumers prefer charges based on flat ratebecause the system has less complications between themand the water utility. Before MWEMintervened, the custom-ers were required to pay their bills regardless of thelevel of service. It is still difficult to justify howlong water flowed in disputed ares and how much water thecustomer consumed. Some places may not receive water fordays or weeks. Water meters are concentrated mainly inareas where water supply is reliable. They are used totest average consumption to develop charging units for thesmall consumers and justify the basis for the bills pro-vided. In areas where water supply is intermittent it is acommon to see non operational water meters. Some have beendestroyed by virtue of vandalism, while some were left in

32

position following failure to obtain spare parts. Defec-tive meter removal exercise may cause extra expenses interms of fittings and replacement of old pipes that canbreak.

NUWA does not have enough facilities for calibration andrepairing meters. The water meter repair workshop builtin collaboration with Lodigiani SpA from Italy is nearingcompletion. It is anticipated that meters will be regular-ly calibrated in the near future to ensure continuedaccuracy. Calibration is required because meters graduallybecome inaccurate with time when in operation. For themeter to work properly, its regular maintenance and cali-bration is necessary. Due to silt problems and low watervelocities in Dar es Salaam water supply, water meterinspection is mandatory during meter reading. There is nocalibration activity being carried out for the time being,except if the customer complaints are to be justified. Thearrangement used can assure only rough accuracy, but cannot be used for continuous meter calibration.

4.3 Consumer knowledge, attitudes and practices

All thirty consumers interviewed were aware of the watermeter use in their service lines. Parker (1988) notedattitudes of the suppliers and the supplied to vary verylittle throughout the world. Without exception allsuppliers want their customers satisfied with the serviceprovided. The supplied take for granted the supplierundertakings and feels that water is a gift of naturerequiring simple process to provide.

Large consumers (mainly industrial) in Dar es Salaam whohave attempted to develop their own water sources realizethe costs involved to supply and maintain the service.Through such knowledge large consumers who have opted todepend on the public water supply will do every effortto support the supplier in maintenance of thewater service. It is uncommon for that matter to findwater meters installed in their premises tampered with.Conversely, few consumers (usually domestic) would riskto tamper with the meter or divert water flow from passingthrough the meter. Exceptions are public service standpipes which are usually not connected to water meters.

The questions asked in the interview were directed toassess the public acceptance of water meter utilization toestimate water cost based on established tariffstructures. It was revealed that water metering isunderstood to be the least disputable method ofestablishing a water cost. It is uncommon to find watermeters in the local market.

NUWA procures water meters through the government storesor through international tenders. Any meter out of servicerequiring replacement means a complicated procurementprocedure requiring foreign currency. Consumers usuallytake advantage of this weakness to break the meters forc-ing NUWAto charge them according to flat rate. Domestic

33

and small commercial consumers prefer this method, becausethey can be assured of using excessive water withoutworrying to pay substantial amounts.

Another cause of vandalism identified was lack ofuniversal metering. The consumer feels to loose money whenpayments are based on water meter reading, while theneighbor is paying less on flat rate though her/his useis similar. Immediate solution is to break, choke themeter or by-pass it. A penalty against such conductsare usually not effective. Usually a customer will berequired to pay all costs for the meter in local currency.As long as water meters are imported, that amount cannotassure replacement of the meter destroyed.

Consumers must be educated and involved in safeguardingwater meters and other facilities. Franceys (1990)commented that unless consumers are involved, systemswill not be maintained correctly and will fail. Waterconsumers in Dar es Salaam have known water meters toregister volumes of air entrapped in their service linesbefore water flows through the tap. This phenomenon ishighly pronounced in areas where water supply isintermittent. NUWAhas constantly advised its customers toclose water taps whenever there is no water flow.

Usually the taps are left open whenever there is no waterflow. In case the water flows the water drops will alertthe consumer to come and store some water ready for thenext dry period. This practice permits the water tap toact as an air valve. The air flows through this tap morefreely than through air valves provided. The quantity ofair passed through the meter is registered. It is true forthe reverse when the water supply is cut, that waterinertia and gravity force may cause backward flow therebycanceling some of the registered readings. The reverseargument is not true for all occasions because it dependson the land topography.

The conflicting behavior of the water meter subject tointermittent water supply is confusing especially to thecustomers who are interested in getting water only. To getrid of this confusion the customers choose to destroy thewater meter or collude with dishonest meter repairers toremove the meter. As long as water meters are not readilyavailable for replacement, the next move is to bill thecustomer based on other estimation methods.

Where flat rates are used, it is a common practice toresell water. Reselling is a means of selling water from aprivate connection or source without any control. Theowner of a private connection can sell water at a higherprice depending on the area and scarcity of thecommodity. Only a small amount of the income which equalsthe flat rate charge is paid as water bill and the rest ispocketed. This denies the water utility to collect revenueequivalent to water supplied. Water reselling in Dar esSalaam is legal.

34

There are about 50 licensed water resellers in variousparts of the city (Mihambo 1992). Water resellers do nottransport water to a customer. The customer comes to buyand transport water by himself. These resellers arelicensed to operate provided they pay the bills preparedagainst meter reading. Legal resellers have a commercialstatus in the utility. They pay their bills according tothe commercial tariff introduced to accommodate thebusiness. Their importance emerged after noticing thatthey extend the service of safe water beyond limits of theutility.

Despite legalizing to resell water, there are fewanonymous resellers who have not registered with NUWA.These are specially found in areas where water supply isnot reliable, and for other reasons the water utility ischarging them according to flat rate. This causes aconsiderable loss of revenue as far as the water utilityis concerned. Usually they do not consider reselling ofwater as a formal business, but sells the commodity oncethe supply resumes. Such resellers are domestic waterconsumers owning a private connection.

Other tricks used to steal water may be summarized as:

a) Illegal connection

This is practiced where agreements have been made betweenthe owner of a private connection and the anonymous user.

b) Periodic jamming or choking of the water meter turbine

Water meters are usually sealed at the factory or afterrepair and calibration. Any attempt to access the workingparts of the meter require breakage of the seal. If thishappens unnoticed its a clear evidence of agreementbetween a zonal meter reader and the consumer. In usualpractice the culprit unchoke the meter periodically andlet few readings be registered to satisfy that nothinghappened to the account holder. Knowledge of the userconsumption pattern and abrupt change of zonal meterreaders helps to identify defaulters.

c) By-passing the water meter

A parallel pipe may be used to divert a certain amount ofwater. This pipe can be buried without water utilitypersonnel noticing unless tipped by someone happening toknow what is going on. Knowledge of the water consumptionpattern helps to identify the tricks.

d) Reversing the meter against direction of water flow

The consumer may fraudulently reverse the meter from timeto time, thus making it run backwards and in this waydrawing unpaid water.

35

4.3.1 Willingness to join and willingness to pay

The mentality of free water services is responsible forfailure of any attempt to assume a total cost recoverypolicy. Already in the early 1970s, Viitasaari (1972)cited by Katko (1991) remarked that it would not be possi-ble to construct and maintain the continuously growingnumber of water supply systems just as a free service.Intensified public education is required to reverse thementality. The government has realized that providing freewater is not sustainable and is now embarked on costsharing approach at least in urban water supplies. Thespirit of project ownership and responsibility among usersis slowly accepted. Still water resources are not utilizedeconomically so that the community would get optimumbenefits out of them.

Accepting to cover water costs by consumers is hardlyrealized because customers feel that the pricing policydoes not reflect equity. Thus expenses of low incomehouseholds are not carefully considered during formulationof tariff structures. The consumers are not educated aboutthe pricing system which results low acceptability ofprices introduced. The consumers have no choice because oflimited alternative water sources. Through water vendingand reselling the public is already paying more thannormal water rates.

While questioning water consumers in areas badly hit byintermittent water supply in the city, it came evidentthat a single household is spending more than TZS 2 000 inan average per month. In such areas like Vingunguti, watervendors use carts with bicycle wheels which can carry upto six 20 1 water containers. Water vendors are thosewho sells and brings water to the customer. The vendorsscoop TZS 20 - TZS 30 per 20 1 of water depending onthe water supply situation. For a family of six requiring30 l/capita/d on an average, it costs the familyTZS 5 400 to 8 100 in 30 days.

The current flat rate requires each household to payTZS 200 to a maximum of TZS 650 per month. The familiespart with this money, otherwise they have to walk longdistances and waste a lot of time for the water they arenot sure to get. This is an indication that waterconsumers are already paying more. Bigger number ofconsumers are willing to join if the services can reachthem. This is explained when the consumers walk longdistances in search of piped water. Alternatively theycould use unimproved water sources.

To hasten the expansion of water services, it may beproposed that economically capable consumers should begiven reliable water services and made to pay enoughrevenue which should be used in expanding and sustainingthe system. The planning of the water supply must reflectthe primary level of service while giving individual usersthe opportunity to pay for higher levels of service ifthey require so.

36

4.4 Effectiveness of water metering

4.4.1 Impacts of water metering

Utilization of water meters have expected impacts. Usuallypositive impacts must outweigh negative impacts in aneconomic selection based on worth-cost analysis. Katko(1991) stressed the need to look into the life cycleeconomics and not only life cycle co~ts. The life cycleeconomy considers benefits and costs over the life time toachieve low cost solutions, though not necessarily forevery area and every consumer. In water supply thebenefits are related to economic effects healthimprovements and other direct and indirect effects.

To realize effectiveness in water metering, meters shouldbe used consistently and universally. This is not the casein Dar es Salaam water supply. Continued utilization ofwater meters in Dar es salaam water supply exhibit theirimportance in the system. The effectiveness of meterutilization in Dar es Salaam is reflected through:

— knowledge of customer water consumption patterns

- established tariff structure based on quantity of watersupplied, unit cost for water supplied at least tolarger consumers can be established at any time

- monitoring water production, distribution andestimating wastage through leakage, illegal connection,public utility, etc.

- data keeping, e.g. daily per capita consumption,percentage of population served, per capita cost ofwater, etc.

Knowing the user consumption patterns have helped NUWA toidentify insincere water meter readers who collude withthe customers to steal water for their personal gain. Ifwater consumption readings obtained through the meterdrops suddenly some doubts must be raised, if the accountholder has not changed. Necessary measures taken mayinclude changing the water meter, changing the zonal meterreader and or checking the entire service line forpossible meter by-passed pipe.

Estimation of domestic water consumption without meteringhas always resulted either overcharging or underchargingof customers. JICA (1991 a), conducted a study bytemporary metering domestic customers in selected parts ofthe city. It was found that water consumption can varysevenfold between households, as found out in Kinondoniarea.

The consumption varied 495 - 3 500 m3 per household perday. In this case, the current flat rates of domesticcustomers, 200 and 450 TZS per month, underrate the waterconsumption of higher consuming customers. The metered

37

consumption has always exceeded these estimations. Itappears interesting to note these effects, and therefore aneed arises to verify the methods used to estimate thedomestic consumption.

As suggested by Sectoral Advisory Team (SAT 1991),domestic consumers should be metered temporarily afterevaluating the cost-benefit of metering. This kind ofapproach is already employed in some parts of Tanzania,e.g. in Tanga municipal water supply.

Industrial, commercial and institutional consumersidentified as large consumers are usually metered. Thosewho remain unmetered are charged according to the averagewater consumption observed when the installed water meterswere operational, or whenever necessary estimating theaverage consumption over a period of time by installingtest meters. This has considerably reduced the water useand effectively used to silence the otherwise would beangry customers.

Once the customers are informed that the tariff structureis developed based on quantities of water supplied, as permeter reading, it helps to accept the structure. Throughwater meter utilization the water authority has been ableto a certain extent, realize surplus water. Surplus waterwhich has been difficult to obtain, is used byredistributing to other users and is measured by expandedservice level.

Monitoring the water production is effectivelyaccomplished. The main problem remains with identifyingthe loss of water in transmission and distribution system.Water meters are not effectively utilized to identifywater losses. Efforts to detect water leakage areaccomplished by the use of physical checking (passivecontrol method) along the pipe line. Discussion with NUWApersonnel revealed that use of water meters in leakagedetection was abandoned due to unavailability of waterdistribution maps and lack of meters and fittings forisolation.

Illegal connections are limited to areas with less meteredconnections. Despite having zonal meters illegalconnections in such areas are difficult to identify. Theauthority occasionally embarks on house to house checkingto identify illegal connections. The recent house to houseconnection survey conducted in Kawe area has enabled theutility to update the masterfile. The survey discovered4 800 connections against the 1 200 known connections (SAT1991).

Dar es Salaam city is expanding faster than the cityplanners can ensure infrastructure service coverage. Watermeters have helped the authority to keep data necessaryfor continued future planning. Such data are daily percapita consumption and per capita cost of water.

38

4.4.2 Tariff structure

Domestic consumers are mostly charged according toestimated water consumption. The charges can vary from theminimum of TZS 200 to a maximum of TZS 650 per month. Theminimum estimated consumption per month is 3 500 gallons(16 m3). The water consumption is estimated by the sub-branch managers and the meter readers.

The tariff structure has been adjusted only twice sinceNUWAwas established in 1981. The tariff structure is notnecessarily adjusted when NUWA requests. Proposals for thenew tariff are prepared annually and decided by MWEM. Thecurrent tariff structure effected in July 1988 based oncategories of consumers is shown in Table 4.

Table 4. Tariff structure in Dar es Salaam (SAT 1991).

Consumercategory

Tariff

TZS/1 000 gal*)

Commercial 192.00Industrial 248.00Institutional 90.00Domestic 57.25

*) 1 000 gal = 4.54 m3.

Figures in Table 5 reflect the real charge per1 000 gallons (4.54 m3) for different customer groups in1984 - 1991. The tariffs have been adjusted with thenational consumer index at 1991 price level. The figuresin Table 5 reflect great decrease, attributable to highinflation rate and infrequent tariff adjustments. Withthis trend of development it is apparent that cash flowmanagement as well as financial planning becomes difficultas income remains the same but expenditures are increasingdue to inflation.

Table 5. Real water charge gallons for different customergroups - price level 1991 (SAT 1991).

Year Rate charged

DomesticTZS/1000 gal

CommercialTZS/1000 gal

InstitutionalTZS/1000 gal

IndustrialTZS/1000 gal

AverageTZS/1000 gal

19841985198619871988198919901991

72.9055.3541.8555.08

345.60268.80230.40192.00

72.9055.3541.8555.08

447.12347.76298.08248.40

72.9055.3541.8555.08

162.00126.00108.00

90.00

72.9055.3541.8555.08

103.0580.1568.7057.25

72.9055.3541.8555.08

264.44205.68176.30146.91

39

4.4.3 Revenue collection

The house to house survey conducted by the Price Water-house in 1989 revealed 43 % of the houses in Dar es Salaamto have been connected to the pipeline (SAT 1991). Thesurvey was deemed to update the customer database ofNUWA. The study identified 55 700 water connections, outof which 32 400 connections were linked to the billingrecord, with 23 300 connections unlinked. This task whichwas conclusively done by the Ardhi Institute in July 1991,revealed 75 300 connections. Of these, 63 700 connectionscould be linked to NUWA records and 11 600 connectionswere found non-existing in the masterfile. Later the wholedata were linked to the masterfile.

Of all the existing connections, only 19 % are paying thewater bills. This was identified from receipts andinvoices prepared in March 1991 for different consumergroups as shown in Table 6.

Table 6. Amount of connections in differentgroups invoiced and receipted in March1991).

consumer1991 (SAT

Consumergroup

Number ofinvoices

Receipts Paid

%

CommercialindustrialInstitutionalDomesticStandpipe

2 833550

1 14958 637

8911

572137298393

18

2025251920

Total 63 258 12 418 19

If the samereceipts inreflected.

consumer1991 (SAT

Consumergroup

Water billsinvoiced1000 TZS

Revenue actuallycollected1000 TZS

Paid

%

Commercial 19 452 8 335 42Industrial 20 148 8 532 42Institutional 23 567 7 785 33Domestic 37 483 25 577 68Standpipe 154 116 75

Total 100 804 50 345 49

comparison is made between the invoices andshillings the figures in Table 7 are

Table 7. Water bills and revenues in differentgroups invoiced and collected in March1991).

40

To reflect the idea that revenue collection is noteffectively done, SAT (1991) made the following simpleestimate:

The city of Dar es Salaam had 345 000 households in 1991,according to Population Census preliminary report. If onlyhalf of the lot is connected to the network, the anticipated revenue collection from domestic consumers (averagerate TZS 325/household/month) per month would be:

(345 000/2)~325 TZS = 56 225 000 TZS/month.

The amount of receipts in March 1991 was TZS 25 577 000and the amount of invoices TZS 37 483 000. This showsuncollected revenue of domestic customers per month in anaverage to be:

TZS 56 225 000 — TZS 25 577 000 = TZS 30 648 000.

The above sum concludes that domestic revenue collectioncould be more than double the amount collected. Withconditions of intermittent water supply, some consumersmay go without water in their pipeline for weeks. Becauseof this The Minister for MWEM, Honorable Lt. Col. JakayaKikwete announced that no payment should be made forunavailable water since April, 1991. This could have anegative impact on revenue collection.

The possibility to prove the availability of water supplycould be through the meter reading. Since these areas arethe ones where meters are not connected (some destroyed toavoid air registration), it would be difficult to estimatethe amount of water chargeable. Likely a great number ofunsatisfied customers will leave water bills unpaid evenif water is running satisfactorily. One suggestion may beintroduction of areal meters or group of households me-tered by a single meter. The monthly consumption can inthat case be divided according to the number of householdsin each group. This may go undisputed if the public iseducated and the whole idea is made clear before implemen-tation.

Revenue collection has not reached the expected level inorder to meet at least operation and maintenance. Hashil(1988) concluded this to result from:

1) failure to workout the tariff imposed on July 1, 1988on a cost recovery basis

2) wrong interpretation and application of charges basedon flat rate system resulting lower charges comparedto metered charges

3) poor customer records.

41

4.4.4 Joint water and waste water billing

According to SAT (1991) joint billing of water suppliedand waste water has not been introduced in Dar es Salaamcontrary to the recommendation by the Price Waterhousestudy conducted in 1987. SAT attributed this to lack ofconfidence by the Dar es Salaam Sewage and SanitationDepartment (DSSD) towards NUWA’s revenue collection.Before the joint billing the study recommended that NTJWAshould first solve the problems of debt recovery,amendments and delays of bills. Due to poor debt recoverythe outstanding balance had reached the level as high astwo billion shillings. According to SAT (1991), debtrecovery is the core problem of revenue collection inNUWA.

The joint billing approach was to be tried in Dar esSalaam and experiences would set as a guide to introducingsimilar approaches in other regions (Mutalemwa 1988). Thecomputer software and hardware currently used by NUWAwereplanned to meet the requirements of both water andsewarage charges collection.

4.5 Practices in operation, maintenance and replacementof meters

Meters in operation will gradually become inaccurate. Therate of decrease of accuracy depends on water quality andtype of meter in operation. Usually meters are providedwith strainers in the water inlet. The function of thefilter is to screen grit particles and.debris that arepresent in water. These filters can assure safety if theparticles are big enough to be retained. Encrustationincreases with time especially when the velocity of wateris very low. Siltation takes place and accumulates insmall openings of the meter assembly. In the long run thisclogs the water meter.

Different frequencies of removing silt and debris in themeter parts have been reported by local meter repairersdepending on the type of water meter and condition ofwaters. The normal routine adopted by NUWA, to clean siltand debris accumulated in any type of a meter is at leastonce in two months.

Dry water meters seldom get affected with siltaccumulation. Wet water meters operate with all workingparts submerged in water being measured. In case of lowwater velocities, settling of suspended matter may result.Added with grit particles that might not be retained bythe filter, the accumulated matter becomes detrimental towater meter operation. The meters should be removed andcleaned and possibly recalibrated to resume theirefficiency. The frequency of removal will depend on thewater source and seasons, with the rainy season requiringfrequent repairs.

42

According to the meter repair foreman, during rainyseasons the meters require cleaning once in two months incase of Dar es Salaam. Silt formation on the meter dialface causes difficulties during reading. Algal growth onthe dial face poses yet another challenge to the meterreader. Such operational problems require substantialinvestment of manpower and financial resources.

NUWAhas a lot of experience in metering. This experienceis vested in individual skills that can be displayed whenfaced with various challenges. For example the waterutility has no workshop where particularly meters shouldbe repaired and calibrated. All repair work andcalibration necessary are conducted at the field. Perhapsthis also contributes to lack of a comprehensivemaintenance and replacement program. Lack of transport isthe common accuse for all kinds of problems, ranging fromlack of disconnections follow up to lack of repair andreplacement of meters.

Bearing in mind the need for human resources to maintainoperational status of projects, the question of incentivesand staff motivation should be given due attention. TheWater Policy available in Kiswahili (Sera ya Maji 1991)developed by MWEMemphasizes on vocational skills. Itadheres to the national policy which recommends thatindividual employers develop their own craftsmen throughsupplementary training programs.

Faced with limited number of skilled staff, NUWA obtainedmost of its professionals through MWEM. Their continuedtraining have been either through MWEM or sponsoreddirectly by International organizations. To the level oftechnicians and craftsmen, NUWA in collaboration withCanadian International Development Agency (CIDA), conductsplant maintenance courses at the Lower Ruvu plant. Thishas helped the authority to obtain specialized skilledpersonnel for various operations.

There is not a particular place where water meterrepairers go for training. They have to relay on theirpersonal innovative skills until the meter suppliers offerto train some. Currently there is only one meter repairforeman who received specialized training in meter repairsin Germany.

Private water companies are almost non existing. This isbecause water supply was initially considered to be asocial service provided by the government. Specialtraining has limited the concerned to remain within theutility even if they lacked incentives. They may lackrequisite qualifications to join other non-waterorganizations in search of green pastures. Since the waterutility still depends on their initiatives to undertakevarious innovative repairs, they can easily paralyze thesystem. Such incidents may be the accumulation of watermeters removed and not replaced in various service lines.

43

The meter may be disconnected to execute waterdisconnection campaign, when rejected by the customeror to undergo workshop repair. This happens because oflack of initiative which results partially as aconsequence of lack of motivation. NUWAhas been operatingwithout facilities for repair and recalibration of watermeters. All related activities have been taking placebased on personal innovative skills which the utilityshould have developed. Developing such skills and honoringthe concerned may tremendously motivate the working force.

Transport is the major problem encountered in executingdaily operations. Employees can spend most of theirworking hours idle while waiting for transport. In somecases the meter repairers carry tools on their shouldersif the job is pressing and very important (Lutende 1992).Walking is limited to short distances and becomesexhaustive when they carry tools and replacementmaterials. Provision of reliable transport such asbicycles and motorcycles in this case is a valuable incentive to the meter repairer.

SAT (1991) noticed the transport as the major cause ofenormous financial losses in the water sector. Accordingto SAT internal report, it was observed that employeesspend most of their working hours idle, while waiting fortransport. The repair of meters cannot be done in timebecause there is no reliable transport allocated to thesection. Whether temporary or permanent metering isadopted, transport facilities should be made available.Programs for maintenance and replacement can not be effectively honored without reliable transport. Investments oncheaper transport, like motorbikes for senior inspectorsand bicycles for meter readers and repairers, could be abetter choice. The benefit is vested in speed, convenienceand favorable prices.

44

5 METERINSTALLATION 2%ND DATA COLLECTION

5.1 Meter installation

Before installing the meters, both site and meterselection was conducted. The sites were selected with thehelp of the NUWApersonnel. The activity included visitingvarious areas identified by considering the status ofwater supply. The required area was to have a continuouswater supply to enable adequate data collection. Thecondition of intermittent water supply is expected everywhere, although some areas may still get water morefrequently.

Another factor considered was security for the watermeters to be installed. Some areas do not get waterthrough their service lines completely within a month,but are required to pay water bills prepared on flat ratebasis. In such areas water meters have either been removedby the water authority or destroyed. The areas affectedmost by intermittent water supply are Tandika, Tabata andVingunguti. These areas were not included in theinstallation strategic zones because the meters would bedestroyed, and therefore jeopardizing development of thestudy. The areas having operational water meters werepreferred because the author had to conduct interviewsrelated to prevailing problems of water meters. The waterutility maintains metering in these areas because throughthem the unit charges for small consumers are developed.This is necessary to justify the rates for the billsprepared.

Excluding the areas with intermittent water supply, thesites were chosen on the merit of: where operational watermeter existed, possibility to install an additional watermeter in series, good accessibility and various use ofwater. Based on these factors the following strategicsites were identified and finally selected (Table 8).

Table 8. Installation sit~es selected and respectivewater uses.

Site identification District Water use

Amana Bar Ilala CommercialAISCO Pugu Road Temeke IndustrialUWT/Zanaki Street Ilala DomesticOysterbay Kinondoni DomesticMorocco Roadbrick factory Kinondoni Industrial

The meters were installed by NUWA personnel. It waspossible to use private plumbers if authority wasavailable from NUWA. Private plumbers originated fromNUWA where they used to work before they were laid-off.They have now formed their working groups with hand toolscapable of doing simple installations. These are accusedto undertake illegal connections and disconnectionspretending to work for NUWA.

45

C—A

Legend:

A = Prototype meter, single/multi-jet, dry dial (Valmet M5-C,Finland)

B = Target meter, multi-jet, wetdial turbine meter (Spanner-—Pollux = SPX, Germany)

C = Target meter, 1) multi-jet,dry dial turbine meter (Kent)2) single-jet, dry dial turbinemeter (Bosco)

1 = 20 nun couplings supplied withthe water meter

2 = strainer for Valmet M5-C watermeter

3 plain socket 20 mm

A-B

A—C

B-A

Figure 10. Proposed alternative connections of the targetmeter and the prototype meter used in thestudy.

46

The target meters were installed according to thestrategic sites earmarked. Those meters which were foundconnected to the service lines were replaced with the samebrand after calibration. Because of limited number ofprototype meters (6) only three brands of target meterswere installed. The idea was that, each target meter wasto be connected alternatively to the prototype meter asshown in Figure 10. Table 9 below summarizes theparticulars of the meters used in the study.

Table 9. Particulars of meters used in Dar esdistribution network.

Salaam

Meter Particularsof the meter

Countryorigin

of Categoryof meter

Kent Qn = 3.5 m3/hSize NS 25 mm,multi-jet, dry

KMJ,dial Un~.ted Kingdom target

Bosco Qn = 1.5 m3/hPN 10, 50 °CSize NS 20 mm,jet, dry dial

single—Italy target

SpannerPollux

Qn = 2.5 m3/hminimum rate =

cold water, 40DIN — ISO 4064Multi-jet, wet

20 1/h°C

dial Germany target

Valmet

ValmetM-5C *)

Qn = 3/5 m3/hSize NS2O mm,jet, dry dial

Qn = 5 m3/hSize NS 20 mm,Multi-jet, dry

single—

dial

Finland

Finland

proto-type

proto-type

*) see Appendix 2 for more detailed specifications.

The target water meters found in the selected servicelines were replaced by new calibrated meters of the sametype and brand. The calibration carried out at theUniversity of Dar es Salaam was aimed to assess theaccuracy of the meters before installation. Arrangementfor calibration included a target water meter whichdischarged the registered water into a flume connectedwith a 600 V-notch. The volumes of water dischargedthrough the target meter were timed by a stop watch andrecorded. The same discharge went through the V-notch. Bycalculating the discharge through the V-notch, volumes ofwater which were supposed to tally with that of the targetmeter were determined. Figures 11 — 13 show the behaviorof the three target meters according to the calibrationconducted.

‘I

Figure 11. Deviation of registration of Boscometer during calibration.

target

- —a-Observed.- —Expected.

,.,

..,- ~—6

,-~-

-

~2-______

~.

~-__

~9’-_

1~~

Figure 1~. Deviation of registration of Kent target meterduring calibration.

47

.E

3

2.5

2

1.5

I

.5

0

—a-- Observed.- —Expected~

U

/9

~X-__ ,,~

D7

U

U

.5 15Meter Readingin Cubq.o

2 2.5 3Meters/hour

II

6

5

4

3

2

1

00 1 2 3 4 5

Meter Readingin Cubic Meters/hour6

48

5

4

3

2

I

0

Figure 13. Deviation of registration of SPX target meterduring calibration.

Installation conducted in six strategic zones were doneaccording to the previous layout. This move was aimed atassessing the installation practices of the water author-ity. Some minor modifications were required to accommodatethe additional prototype meters (Figure 14).

After each installation water flow was tested to ensurethat water supply was normal. Intentions of the doublewater meter installation were explained to respectivecustomers to maintain good relations. Knowing the previouswater meter, the customer was also acknowledged thatcharges will be based on that same meter.

.~

MeterReadingin CubicMeters/hour

t

49

a)

b)

Figure 14. Installations of the meters in the Dar esSalaam distribution system.

5.2 Data collection

Data collection was carried out with the help of meterreaders from NUWA. This enabled the assessment of themeter reading system. The meter reading system used in Dares Salaam water supply is direct reading. This method isused to record readings manually after physically

50

observing the registered volume on the meter. The readingsmust be clearly visible to enable the reader to record theactual figures observed. Otherwise the reader has toestimate the readings thereby defeating the whole purposeof metering the service line.

In Dar es Salaam distribution network meters are supposedto be read once per month. For the purpose of this studydata were collected once per week. Meter readers fromthree N~JWA branches (Temeke, Ilala and Kinondoni)collected data independently. The investigation focused onthe following:

1) readability of the water meter2) quantities of water registered by each meter3) water quality effects on meters4) other effects on the meter, e.g. effects of tempera-

ture, humidity, solar radiation, etc.

The data collected mainly concerned relating theconsumption of water as registered by the two meters inseries. The law of mass flow require the two meters toregister equal volumes of water at any time. Other factorswere investigated to determine how they affect theperformance of the meters as well as the reading method.Subjected to the same environment it is expected that eachmeters would be affected equally. If this is not the case,a reason should be sought and analyzed to determine itsvalidity.

SPX meters collected from Tanga were accused of poorreadability mainly due to accumulation of silt on the dialplate and registration of air as a result of intermittentwater supply. Figure 15 shows the situation when themeters are disconnected from the lines ready for service.In this situation one may wonder if the last reading wascorrectly recorded or estimated. After installing themeter, the same manifestation of the silt formation on themeter dial face was observed. Although the meter was stillreadable, it was enough to conclude that the meter willnot be clearly read in the long run.

t

51

-=

~ .- aW ~

~•‘-.aJ••~

I.)

. ~

~g%r•-~i .~-~~.‘:!7~ :•~~i~%t..

-~ ,--

Figure 15. SPX meters removed from the service linesready for repair in Tanga.

Apart from siltation problem, the SPX meter formed a watermeniscus as a result of low water pressure. The meter isto run full of water all the time. If there is lowpressure, the meter shows sections which have water andthose without. This results in poor readability, requiringmore attention and time to accomplish the exercise. Thefog or moisture formation under the glass was not a sig-nificant problem for the SPX meter. When water runs fullin the meter it collects all the droplets under the glass.This may be proved to work better after a long time obser-vation -

The Bosco meter’s poor readability was caused by the fogformation under the glass. The design does not permit thewater flow over the meter dial face. For the Bosco meterdesign a mechanism to wipe water droplets under! theglass would be appropriate. According to retired watermeter repairers, this kind of mechanism was used in olderversions. The mechanism constituted a turning knob overthe glass and linked to the wiper under the glass. In casethe meter reader failed to read due to fog, the knob wouldbe turned once to clear the glass.

The Kent and the prototype meters were read clearly duringthe observation period. These designs are sealed againstwater and moisture from entering the glass-dial interface.All meters used in the study were easily read without theneed for manipulations or special skill.

52

6 ANALYSIS AND DISCUSSION OF RESULTS

Tables 10 - 14 show results of the respective consumptiondata registered by various meters.

Table 10. Consumption as registered by SPX domestic meterversus the prototype meter based on volume onsite UWT Road/Zanaki street.

Timeinweeks

Volume registered *)

Prototypem3

Registered difference **)

m3 %Targetm3

1 6.72 6.44 — 0.28 — 4.352 4.49 4.36 — 0.13 — 2.983 5.36 4.35 — 1.01 — 23.224 4.06 4.89 + 0.83 + 16.975 3.80 3.88 + 0.08 + 2.066 3.91 3.79 — 0.12 — 3.17

Total 28.3 27.714 — 0.04 — 0.14

*) series connection with water flowing through SPXmeter first

**) the positive sign indicate that the target meter hasregistered more.

Table 11. Consumption as registered by Bosco domesticmeter versus the prototype (multi-jet) meterbased on volume on site UWTRoad/Zanaki street.

Timeinweeks

Volume registered *)

Prototypem3

Registered difference

Targetm3 m3

123456

9.606.887.869.247.967.15

4.132.734.322.253.544.10

— 5.47 —

— 4.15 —

— 3.54— 6.99 —

— 4.42 —

— 3.05

132.45252.01

— 81.94310.67124.86

— 74.39

Total 48.69 20.64 — 28.05 — 135.90

*) series connection with water flowing through Valmetmeter first

53

Table 12. Consumption as registered by Kent domesticmeter versus the prototype meter based onvolume on site Oysterbay.

Timeinweeks

Volume registered *) Registere4 difference

m3 %Targetm3

Prototypem3

123456

75.4633.0440.2943.5135.3226.78

72.5031.2637.8640.7332.9525.33

— 2.96— 1.78— 2.43— 2.78— 2.37— 1.45

—

—

—

—

—

—

4.085.696.426.837.195.72

254.40 240.63 — 13.77 — 5.72

*) series connection with water flowingmeter first

through Valmet

Table 13. Consumption as registered by Kent commercialmeter versus the prototype (multi—jet) meterbased on volume on site Amana Bar—Ilala.

Timeinweeks

Volume registered *) Registered difference

Targetm3

Prototypem3 m3 %

123456

59.5030.8044.5019.1323.3110.62

60.2231.0648.7220.9925.6119.63

0.790.264.221.802.309.01

1.200.868.668.588.98

45.90

187.86 206.23 18.37 8.91

*) series connection with watermeter first

flowing through Kent

54

Table 14. Consumption asmeter versusvolume on site

registered bythe prototype

AISCO Pugu Road.

SPX industrialmeter based on

Timeinweeks


m3 %Targetm3

Prototypem3

123456

32.6024.3032.8026.8826.3922.12

31.8424.0128.8321.3328.7722.49

—

—

—

—

+

+

0.760.293.97 —

5.55 —

2.380.37

— 2.39— 1.21

13.7726.02

+ 8.27+ 1.65

Total 165.09 157.27 — 7.82 — 4.97

*) series connection with water flowing throughmeter first -

Table 15. Consumption asmeter versusvolume on site

registered by Boscothe prototype meter

Morocco Road.

industrialbased on

Timeinweeks


Targetm3

Prototypem3 m3 %

1 36.94 37.19 + 0.25 + 0.672 7.00 6.87 — 0.13 — 1.893 38.43 34.18 — 4.25 — 12.434 31.28 27.21 — 4.07 — 14.965 31.03 11.15 — 19.88 — 178.30

Total 144.68 116.60 — 20.08 — 24.08

*) series connection with water flowing through Boscometer first

The data in Tables 10 - 14 reflect the true picture of theproblem predicted before implementation of the fieldstudy. The question here should be viewed as to theperformance of the two meters connected in series subjectto the same conditions of: water quality, intermittent

humidity, solar radiation, pressurewater supply,fluctuation, etc.

In view of the above the following observations were made:

1) Any of the water meters connected in series with theprototype meter do not register equal volumes contraryto the law of mass flow (Figures 16 - 21).

S

Valmet

55

7.5LwciE

I ~-°o 2..5

aE

In

0U -

Figure 16. Consumption as registered by SPX meter versusprototype meter based on volumes.

10.0

E 75U

n

Weeks

~~raph BTARGET

Craph APROTOThPE

Figure 17. Consumption as registered by Bosco domesticmeter versus prototype meter based on volumes.

1 2 3 4 5 6

~~raph 8TARGET

Graph APROTOTYFE

Wee k~

1 2 3 4 5 6

56

In

wci

EU

~0

U

0

aC

U~i

C

0U)

Figure 18.

In

ci9—ciC

U

Figure 19.

Consumption as registered by Kent domesticmeter versus prototype meter based on volumes.

Consumption as registered by Kent commercialmeter versus prototype meter based on volumes.

80

60

40

20

U

I

1 2 3 4 5 6

~Graph ATARGETGraph FPROTOTYPE

Weeks

75

~50

25

01 23456

Weeks

~Graph BTARGET

Graph APROTOTYFE

57

40ci4-,

ciC

U 30nU

C 20

C0

Figure 20.

In

ci

U

1~3

:3

U

C

C0

P-.

aC

:3

Ui

C0

U)

Consumption as registered by SPX industrialmeter versus prototype meter based on volumes.

Figure 21. Consumption as registered bymeter versus prototype meter

Bosco industrialbased on volumes.

2) All meters with their initial positions interchangedregister unequal amount of water contrary to the lawof mass flow.

3) The prototype meter register smaller volumes of watercompared to the target or reference meters. Anexception case indicated only with the Kent meterinstalled in vertical position with the prototypemeter installed in horizontal position (Tables 12 and13).

~Graph ~TARGET

GrapH APROTOTYPE

1 2 3 4 5 6

Weeks

40

30

20

10

01 2 3 4 5

~Graph BTARETGraph APROTOTYPE

Weeks

58

4) Only Kent meter showed a unique characteristic afterinterchanging the installation position. That is thedifferences in volume registered remained positive forone position and negative for the other position(Tables 12 and 13).

5) Bosco meter showed relatively higher percentage ofvolumes registered compared to the rest of the targetor reference meters (Tables 11 and 15).

6) SPX meter showed the smallest percentage differencesrelative to the rest of the target meters (Tables 10and 14).

From the above observations the following may beconcluded:

1) During data collection the water supply wasintermittent. All meters being turbine or vane typemust show the same characteristics of air registrationbecause of the same design features. Since the targetmeters showed relatively higher values of volumes, itcan be concluded that air registration is dependent onthe sensitivity of the meter. It may be true that thetarget meters have higher sensitivity compared to theprototype meter. This phenomenon did not change afterinterchanging the meter position.

2) Since the prototype meter has generally shown toregister less than the target meters (Figures 16-21),it may be true that the counting threshold of thismeter is higher than that of the target meters. Thisis the maximum amount of water that can pass throughthe meter without being registered. These resultsemphasize that meters should be a bit robust and nottoo sensitive in conditions of intermittent watersupply.

3) Installation has an impact on the performance of themeter. The installation of the Kent meter in verticalposition changed the trend of observedcharacteristics. In the vertical position the Kentmeter registered less than that in the horizontalposition. The meter installations are specified by themanufacturers.

When the metes are procured through government stores,the technicians do not bother to request for theinstallation specifications. In this case it is likelythat there was no specification provided, usually thetechnicians responsible for meter installations assumeto know the specifications by experience. Once thespecifications require otherwise, the mistake cancause inaccuracy of the meter falsely installed.

4) The alternating positive and negative differencespredict that siltation may have affected theperformance of the meter. The filters provided canonly retain grit particles to a limited size. The rest

59

of the particles may settle in between the meter partsdepending on flow velocity of water, settling velocityof the particle, and the surface area available. Thesettled particles between moving parts can hinder andclog the meter.

5) The pressure fluctuation did not cause considerableharm to the meter. Since the pressure cannot beconstant throughout, loss of accuracy might haveresulted. The arrangement did not permit detection ofpressure effects on meter accuracy.

6) Water quality effects on the working parts of themeter may be witnessed after a long run. This willrequire disconnecting the water meter from the serviceline and investigating the parts against tear andwear, meter parts - water reaction, etc. One of theresults expected from the SPX meter is some sort ofreaction between the meter dial face and the water.This unknown effect is being experienced on SPX watermeters in Tanga urban water supply (Figure 22).

Since the meters have been in operation for two monthsonly, it was too early to judge whether or not thesame effects will happen to the meter. For thismatter, the water meters have been left connected inthe service line and will be maintained according toNUWA practices. To substantiate the complaintscontinuous monitoring of the meters will be required.

Figure 22. Reaction of the meter dial face with the waterin Tanga municipal water supply.

60

7 CONCLUSIONSAND RECOMMENDATIONS

Dar es Salaam water supply has remarkable experience ofwater metering. Through metering and application ofestimation methods the water authority has been able torealize some benefits vested in meter utilization. Theresponsible authority has applied the metering partly atleast for the big consumers. In view of the study thefollowing may be concluded:

1) Water metering by itself does not control UFW, butrather helps in identifying whether UFW problems existbefore deciding to invest on control measures.

2) Debt recovery identified to be the core problem in Dares Salaam is a management problem. To realize aneffective cost recovery, and appropriate policy shouldbe established and effectively executed.

3) Water meters can help to determine the unit cost ofwater supplied, and hence to develop and appropriatetariff structure based on actual water consumption.Based on this fact NUWAhas considered it appropriateto meter selected customers with an objective toestablish a water charge for non-metered consumption.This is a commendable approach which can effectivelybe used to off-set the substantial investment of watermetering.

4) Water vending and reselling taking place in Dar esSalaam is a clear indication that water supplied doesnot satisfy the demand. The higher costs of waterthrough reselling managed by the people predictswillingness to pay and join the water supply. Ifcorrectly applied, water metering may create a savingin water that can be used to expand the service area.With the prevailing capacity, it is wise if thepractice of water reselling can be left under thecontrol of NtJWA.

5) Unreliable or inadequate water services encouragevandalism. Water meters are mainly destroyed in areaswhere customers do not receive adequate waterservices.

6) In part of the problems existing in water metering,inappropriateness of water meters has proved to be acontributing factor. The field study conducted showedthat meters in operation are not performing asrequired. None of the tested meters showed equalvolumes against the prototype meter installed inseries. Also some of the water meters showed poorreadability which may be continue to be worse due topoor water quality. Although the meters were notinvestigated against the effects of water quality onthe working parts, the over—registration and under-registration against the prototype meter predictedwater quality effects. Turbine meters despiteregistering air are more appropriate to be used inturbid water than the positive displacement meters.

61

Single-jet, dry dial turbine meters are in principlethe most suitable meter type, provided that they haveadequate protection against external disturbance(vandalism, manipulation of readings etc.) and haveadequately high counting threshold to avoid airregistration.

7) Meter operation and maintenance problems in Dar esSalaam water supply are mainly due to lack of adequatetransport, spare parts, replacement meters, poor waterquality and intermittent water supply. The watersupply system has a variety of water meters inoperation. These meters imported through variousprograms have always complicated the procurement ofspare parts and replacement meters. Dar es Salaamwater supply like any other water utility indeveloping countries cannot cope with the developmenttrend of the meter industry. This is due to pooreconomy which usually necessitates them to pursuemaintenanceby crisis and not by programs established.Cheap labor is available but not cheap spare parts. ifwater meters are standardized, it is easy to procurespare parts and replacement meters, easy to mastertheir maintenance and easy to transfer the tech~nologyfor local manufacture of appropriate meters.

8) The study conducted indicates a good possibility for aworking cost-recovery. The willingness to pay and joinis very high as envisaged through vending andreselling of water. The major problem is debtrecovery.

9) On the appropriateness of the water meters, the studyshowed that meters used in the distribution network donot perform well under the local conditions. Underthese conditions it is concluded that an appropriatemeter should:

a) not register air as a result of intermittent watersupply

b) be easily repaired with parts capable of being

reused several times

c) be easily readable without any manipulative skills

d) have a strong but simple construction and not

attractive for vandalism of theft

e) not form fog or any water bubbles under the glass

of the meter thereby causing poor readability

f) be easy to install in any position without causing

loss of accuracy of the water meter -

g) withstand fluctuation of pressure without loss of

accuracy

h) be resistant to corrosion, abrasion and otherreaction, related effects of water quality.

62

It was observed that the amount of UFW in the water supplynetwork ranges from 35 % - 40 % and the attempt to controlthis was thwarted by lack of water meters. Also observedwas the lack of effectively followed replacement,operation and maintenanceprograms due to prohibitivecosts involved.

To ensure sustainability of standard water services andreduced UFW, it is recommendedthat:

1) Passive control method practised be enhanced andaugmented by the district metering control methodwhere leakage cannot be easily noticed. For thispurpose the districts established may be considerablylarger necessitating the use of fewer meters.

2) NUWA should concentrate on temporary metering ofconsumers capable of generating revenue that can helpoperation and maintenance of meters. Water meterbrands should be reduced through standardization toreduce complications in procurement procedures.

3) Evaluation of water meter utilization should beconducted to establish non-quantifiable benefits. Thesaving in water due to water meter utilization can beused to expand service capacity.

B4) Debt recovery should be given priority. Monthlybilling should not include the balance of the previousmonth. To enhancedebt recovery, penalty of not lessthan the inflation percent should be imposed on unpaidbills. The public and particularly the customers mustbe educated through the news media. Advance billingshould be used to speed up the cash flow and improveprofitability.

5) To complete the study and prove the complaints overappropriateness of the meters, long time investigationof the meters should be conducted. The meters left inthe distribution can be used to derive some of thefactors that could not be accomplished due to timelimit. In fact the study has proved that the metersused are not appropriate for our local conditions.

63

8 REFERENCES

Albro, D. D. 1985. Small meter installations and periodicmeter testing. AWWA seminar on customer meteringpractices. Annual conference. American Water Works -

Association, Washington D.C. p. 11 - 20.

AWWA (American Water Works Association). 1986 a. Watermeters selection, installation, testing and maintenance.AWWA, Denver. p. 28 - 30.

AWWA (American Water Works Association). 1986 b. Sizingwater services, lines and meters. Manual for water supplypractice. AWWA, Denver. p. 3 - 48.

Bays, L. 1984. Leakage control. Aqua, no. 1. p. 51 - 55.

Bhattacharya, S. D. 1982. Minimum satisfactory quantityand quality of urban domestic water supply in developingcountries. Doctoral thesis. Loughborough University ofTechnology. p. 249 - 259.

Brainard, F. 5. 1985. Large meter installations and fieldtesting. AWWA seminar on customer metering practices.Annual conference. American Water Works Association,Washington D.C. p. 21 - 33.

Franceys, R. 1990. Paying for water - urban water tariffs.Journal Waterlines. Washington D.C. p. 9 - 11.

Hashil, H. A. 1988. Prevailing practices in operation andmaintenance of urban water supplies. Proceedings 10thAnnual Water Engineer’s Conference (AWEC), Mbeya,Tanzania. p. 143 - 147.

Jeffcoate, P. and Pond, R. 1989. Large water meters,guideline for selection, testing and maintenance. WorldBank technical paper no. 111. Washington D.C. p. 81 - 84.

Jeffcoate, P. and Saravanapavan,A. 1987. The reductionand control of unaccounted-for water. Working guidelines.World Bank technical paper no. 72. Washington D.C. 128 p.

JICA (Japan International Cooperation Agency). 1991 a. thestudy on rehabilitation of Dar es Salaam water supply inthe United Republic of Tanzania. Final report. Vol. 2,p. 2.16 — 6.30.

JICA (Japan International Cooperation Agency). 1991 b. Thestudy on rehabilitation of Dar es Salaam water supply inthe United Republic of Tanzania. Final report. Vol. 3,p. A1.5 — A1.17.

Katko, T. S. 1986. Major constraints in water supply indeveloping countries. Aqua Fennica 16,2: p. 231 - 243.

Katko, T. S. 1989. The role of cost recovery in watersupply in developing countries. Publication of TampereUniversity of Technology, Institute of Water andEnvironmental Engineering, no. A 41. p. 120 - 130.

64

Katko, T. S. 1991. Paying for water in developingcountries. Doctoral dissertation. Publication of TampereUniversity of Technology, no. 74. p. 18 - 70.

Kent Meters Limited. 1988. Domestic and industrial meters.Technical manual. p. 2.

Lindh, G. 1983. Water planning and management:Better useof water resources requires planning. Journal Water andthe City. p. 50.

Lutende, N. 5. 1992. Personal communication.

Manson, J. 1989. Metering on trial. Journal Water andTreatment. p. 31 and p. 37.

Mihambo, D. M. 1992. Personal communication.

Mutalemwa, A. R. 1988. Prevailing practices in operationand maintenance of sewerage systems in Tanzania.Proceedings of the 10th Annual Water Engineer’s Conference(AWEC), Mbeya, Tanzania. p. 148 - 151.

Mäntylä, M. 1991. Personal communication.

O’Day, D., Weiss, R., Chiavari, S. and Blair, D. 1986.Guidance manual, water main evaluation for rehabilitationand replacement in distribution systems. American WaterWorks Association ResearchFoundation, Denver, Colorado.p. 37 — 54.

Parker, B. E. 1988. Communicating with the customer.General report. Wessex Water Authority, Bristol, England.p. GR 2 - 2.

SAT (Sectoral Advisory Team). 1991. Strengthening Ministryof Water Energy and Minerals, towards achieving water andsanitation sector objectives. United Republic of Tanzania.Project URT/89/003/. Quarterly report. p. 3 - 28.

Sera ya Maji. 1991. Wizara ya Maji, Nishati na Madini.Tanzania. p. 42 - 46.

Smith-Vargo, L. 1989. Water meters: turbine vs compound.Journal Water/Engineering and Management, November 1989.p. 44 — 47.

Steel, E. W. and McGhee, T. J. 1979. Water supply andsewerage. McGraw-Hill International Editions. Auckland.p.15 — 16, p. 132 — 133 and p. 591.

UNDP-World Bank. 1990. Water and Sanitation Program. Workprogram. Country work plan. Vol. 1, p. 78 - 79.

Van der Zwan, J. T. 1988. Water transportation anddistribution. Operation and maintenance of networksystems. Publications Water Works, Testing and ResearchInstitute. Nieugein. p. 28 - 30.

Viswanath, A. and Kazufumi, M., 1991. Rehabilitation planfor the Dar es Salaam water supply system. TokyoEngineering Consultants Co. Ltd., Tokyo, Japan. p. L-2.

65

APPENDIX 1 (1/4)

INTERVIEW SCHEDULEFOR EVALUATION MID DEVELOPMENT OF ANAPPROPRIATE WATERMETERFOR DEVELOPING COUNTRIES

The interview schedule is based on a checklist ofpriority questions. It was recognized that some of thepriority questions appeared in both side of the customersand the water utility.

It was not feasible to use the broad main question inan interview or observation. Each main question isto be disaggregated into a number of sub-questions. Theanswer to all sub—questions for each question would thengive a valid answer on the originally formulated mainquestion.

This exercise resulted 6 main questions for the customerand 8 for the water utility. All priority questionsfell into one of the following groups, reflecting animportant aspect of the water metering system.

I Ownership and security of water metersII Understanding of the water metering objectivesIII Appropriateness of the meterIV Justification of the metering policyV Practices in the metering system

1. PRIORITY QUESTIONS FOR THE CUSTOMER

1) Do you understand the water metering objectives?

— Do you have a water meter connected to your waterservice line?

- Do you understand the objective of connecting thisdevice to your service line ?

- Does the water bills you receive have any relationwith the water meter reading?

- Before you proceed to pay your water bills do youcross check recorded reading and the current meterreading?

— How do you use the water supplied?

2) Who owns the meter and what measures are taken toensure the security of the water meter?

Sub-questions

- Did you buy this meter yourself? Yes ( ) No ( )- If no, who owns it?- Did you pay any fee to have the meter installed to

your service line? Yes ( ) No ( )- If yes, how much?- Should the fee be paid anyway?- How do you feel about the security of a facility

you don’t own or not rented to you?- How do you care if it went out of order?

66

APPENDIX 1 (2/4)

3) What sort of problems do you face on using meters?

Sub—questions

- Do you like to continue using the water meters?— Does meter utilization cause any inconvenience to

you?

4) Is the water meter appropriate for your use?

Sub—questions

- Are you aware that a meter can under-register orover—register?

- Have you ever experienced any discrepancy in theperformance of any meter you have used?

— What complaints do you have over the meter?

5) Do you think the meter utilization is effective?

Sub—questions

- Do you pay according to what you use?- Should the water meters be used?- What should be improved to enhance efficiency in

the metering system?

6) What are the tricks used to evade actual billsaccording to water supplied?

Sub-question

- Do you know that some water is lost through the system?— Are you aware that theft of water accounts to these

losses?- Do you know any tricks used by your neighbors to

use water that can not be billed?— What suggestion do you have to reduce such losses?

67

APPENDIX 1 (3/4)

2. PRIORITY QUESTIONS FORTHE WATERUTILITY

1) What is the use of water meters in your distributionsystem?

Sub-questions

- What type of metering do you undertake?- Is the whole distribution network metered?— How do you make your priorities in selecting

customers to be metered?- How do you monitor water losses?

2) Do you own all water meters in the distributionsystem?

Sub-questions

— Is it possible for a customer to procure and askyou to install it in the service line?

— Do you charge any rental fee for each meterconnected?

3) How do you ensure security of meters?

Sub—questions

— Do you experience vandalism caused to water meters?— What measures do you take against such incidence?- Do you have precautionary measures to avoid

possible future incidents?

4) Do you find it necessary to use water meters?

Sub-question

- What are the methods you use to establish a water cost?— Does the water metering play any important role?— How is your relationship with the customers

a) those who are using water meters ?b) those who are not using meters?

— How does the water meter use help in forecastingwater demand ?

68

APPENDIX 1 (4/4)

5) Do you find water metering cost effective?

Sub—questions

- Are all water meters installed operational?- Does the Authority benefit compared to the costs

involved in installation, operation and mainten-ance, and replacement of meters?

- Do you think the water authority should invest morein the metering system?

6) What are your opinions over the meter reading systemused in your authority?

Sub—questions

- Do you feel that the system of meter reading isefficient to effect timely and precise billing?

- What are the setbacks in your meter reading system?What is the frequency of meter reading?

- Do you believe that all meters are read accordingto records provided?

7) Do you know any tricks used by customers using metersto steal water?

Sub—questions

— Are you aware that water meter users use tricks toconsume water without the meter system?

- How do you net culprits who use tricks to increasenon—revenue water?

- Are all metered customers free to use any amount ofwater?

8) Do you find meters used to be appropriate ?

Sub-questions

- Do you have any operational or maintenance problemswith water meters?

— How often do you repair and replace meters?- How do you know that the water meter is not

operational?- Do you know any complaint from the metered customer

regarding meter performance?— What is your opinion regarding the appropriateness

of these meters?- What are the basic problems you face with them?— Do you have any complaint over any particular type

or model of the meter?

69

PROTOTYPEWATERMETERSPECIFICATIONS

Valmet M-5C

Wide-flow-range water meter NS2O 3/5 m3/h

APPENDIX 2

multi-jet inferential dry dial vane wheel meter

5-digit roll counter enclosed in a case

eccentric rotor at center face directly coupled to vanewheel for easy checking of meter, and 3 pointers: 1 1,10 1 and 100 1

mounting dimensions according to DIN 3260 standard

connections with thread

two years’ guarantee.

Specifications

Permissible continuous loadPermissible short-duration peak loadPressure drop with nominal flow 5 m3/hMaximum error of measurement- from lower limit to medium limit- from medium limit to upper limitLower limit of measurementMedium limit of measurementCounting thresholdCounter- smallest reading- largest readingOperating temperature, max.Operating pressure, max.Test pressureMaterials- body- measuring machinery— strainer— connections (ordered separately)ColourMounting

Weight- meter, length 190 mm- meter, length 220 mm

5 m3/hunlimited0.95 bar

± 5%± 2%20 1/h150 1/h5 1/h

0.001 m3100 000 m340 °C16 bar24 bar

chilled brasspolystyrene, polyamidepolyethylenebrassgolden bronzehorizontally withthread connectionsR1/2K or R3/4K

1.7 kg1.8 kg

70

APPENDIX 3 (1/3)

Table 16. Domestic consumption of water as registered byBosco meter versus the prototype meter Zanakistr/UWT Road site.

Date Meter reading Observational remarks

Bosco Prototypem3 m3

5.12.1991 27.65 17.54

16.12.1991

22.12.1991

29.12.1991

37.26 21.67

44.14 24.40

52.00 28.72

Readability of the Boscometer was poor due tomoisture formation underthe meter glass.

5.1.1992

12.1.1992

61.24 30.97

69.20 34.51

The area experiences lowwater pressure and fairlycontinuous water supply.

19.1.1992 76.35 38.61

Table 17. Domestic consumptionSPX versus prototypesite.

of water as registered bymeter Zanaki str/UWT Road



5.12.1991 16.37 14.05

16.12.1991

22.12.1991

29.12.1991

23.09 20.49

27.58 24.85

32.97 29.20

Readability of the SPXmeter was poor due toformation of the watermeniscus between themeter glass and the dial.

5.1.1992 37.00 34.09

12.1.1992.

19.1.1992

40.80 37.97

44.71 41.76

The area experiences lowwater pressure and fairlycontinuous water supply.

I

71

APPENDIX 3 (2/3)

Table 18. Commercial water consumption as registered byKent versus prototype meter on site Amana Bar -

Ilala.


Kent Prototypem3 m3

5.12.1991 51.40 52.35Readability of both

16.12.1991 110.90 112.57 meters were very good.The meters were dirty

22.12.1991 141.71 143.63 revealing that peoplewere accessedto it. The

29.1.1992 186.20 192.35 installations were notsafe against possible

5.1.1992 205.33 213.34 vandalism.

12.1.1992 228.64 238.95 Water supply was inter-mittent during the time

19.1.1992 239.26 250.58 of study.

Table 19. Domestic consumption as registered by Kentversus prototype meter on site Oysterbay.


Kent Prototypem3 m3

5.12.1991 153.0 145.30

16.12.1991 228.46 217.80 Readability of bothmeters was good.The area

22.12.1991 261.50 249.06 was safe againstvandalism.

29.12.1991 301.79 286.92

5.1.1992 345.30 327.65 Water supply was observedto be fairly continuous.

12.1.1992 380.62 360.60

19.1.1992 407.40 385.93

72

APPENDIX 3 (3/3)

Table 20. Industrial consumption as registered by SPXversus prototype meter on site AISCO Pugu Road.


SPX Prototypem3 m3

5.12.1991 44.81 43.17 The area received fairlyconstant supply.

16.12.1991 77.37 75.04 The meter readability waspoor due to water

22.12.1991 101.68 99.05 droplets formed underthe glass.

29.12.1991 134.15 127.88

5.1.1992 161.38 149.21 The installation was safebuilt underground and

12.1.1992 187.77 171.98 within the fence.

19.1.1992 209.81 194.47

Table 21. Industrial water consumption as registered byBosco versus prototype meter on site MoroccoRoad.



5.12.1991 85.24 84.37 Fog formed under theglass after installing

16.12.1991 122.18 121.56 meters.

22.12.1991 — 124.40 Missed data due tolock-out. Owner locked

29.12.1991 129.10 128.43 to avoid misuse of waterin his absence.

5.1 .1992 167.16 162.61 The area experiencedintermittent water

12.1.1992 189.82 198.89 supply occasionally.

19.1.1992 220.85 210.04

73

APPENDIX 4

Legend

——

- -.-- ~

— Water Treatment Plant

• Reservoir

Trunk Transmission Line

Area Served byDistribution System

o

Water supply system of Dar(Viswanath and Kazufumi 1991).

es Salaam

/

———-——

0

St —

S ~ ~ :i~•’ 4

I

e Dn~er~ftof T~n~l~y f~’pT~

gnd Eavirnn~nta1 ~nr~.theerinai cation Series B

~ ~ o2tion~ in rural water s~pply in developingi-P~-~--Woric.sriop report. 51 p.

~~S~4Olainen, ~. 1987. Zimastetun lammikpn tehokkuus metsäteollisuuden jäte-

~n~r~enk~ ja ki~tQ~n~~pgistossa map~~,-

________ • ei~~ ~ (BQD ~ ~u~ended ~ ~~Qya1 ~~ençy

ii’ j 2~w~t~iatina pulp and papçr ~ll effluent~eya1uated byth~iñätical models). 30 p. Original in Finnish.

jM~

S. 1~7~ y ~laj1 ~ tj~~tta~jp~ ~ansajr~y~1jsil1~

~‘fl~!~liii ~ ~ ~ çn~~e~ri~a~esea~ç~ r~ult~ inç~~sses and lournals). 72 p. Original p~rtly in English—- ~,à.L Ly ].fl Finnisn.

_____ S. 128~~~~lic~bi~itv c~ ~ sewers. in A~ddjs Ababa,lopia. 47 p. MSc thesis.

~ I ~cestina QLthe cof muiti-staqe~wirli,. N~ctnes~.s.

~. ~ ~ a~d~eakfaçto~ with reference to_____ wa er supp y in ~thiopip. 61 p. NSc thesis.

12~ ~n~n~a mQ~t~tion unit ~forjthe water resourcesTanzania.68 p~MSc thesis.

i~W~~e?- ~ ~R~al ~ ~u~p1y d~v~lopm~pt in~jseug~ ~i~Jo~ ~it~ne~ ~o~essa; slt~vi~.-~ s~n~~ ~ ~e~lopir~ ~ - Discussion p~per).

na.LpartLv in Finnish and partly in Erig].ish.

~ vi~Irf~flLB. i98~A ~jent of tannery wastewaters by activated sludge~UI- p. ~c tnesis.

- ~ ~ ~ ~ rur~ ~ ~u~ly in Finland: Possible________sons or tue developing world? - Discussion paper. 49 p•

1~2!Teo~~J~~ ~ ~~tii~~ - ~ (t~ra~~e 3

2j~ of ~nae~b~c~j~~trial wastewaters at thermophilic temperature). 35 p.

~innis.~..

~w~m~ flt~vt~ Qf ‘~flr/Ifl8titutg of Wa’ter and

~ fl~ç~ 60Q~ — (~11Lthrarv ____________________________________Ij_~:ii i~1~ ~ t~ ~11~11i..__- 1 ‘~1~e FINLAND ~•-~1O1 ~~n~je1 ~~ND+ 1 ______ ~ ~ ~1 1~U62

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water metering developmentin dar es salaam, tanzania - irc3 jigabha, j., 1992. water metering...

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