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ResearchThe Revenue Effect of Inefficient Potable Water Meters on a Water Utility Co

BackgroundFor many years, utilities and water professional researchers have been trying to determine the optimum time for meter replacement with no conclusive answer Davis, 2005, p. 3Significance of the StudyServe as measurement units and cash registers in any modern water-conscious utility.

The majority of water utilities throughout the world provide their customers with water meters to measure their potable water consumption. Inaccurate meters tend to under-register consumption volumes and therefore a water utility should monitor closely customer consumption trends to identify meters that have lost accuracy.

The primary purpose: to provide a basis for water user fees for the majority of the utilitys revenue

Non Revenue Losses are approx 68%

Suffers from the inability to recover the full cost of service from consumers, partly due to inadequate tariffs as well as excessive losses and inefficiencies. (Smith, 2011, p. 6). The National Water CommissionThe National Water CommissionWater production: 24.09 billion Litres

Billed volume: 8.18 billion Litres

LOSSES 15.91 billion Litres

Leaks, OverflowsTheft,Acc. ErrorsMeter ErrorsPhysical ApparentThe Water CompanyActive Customer base: 334,337Possessing meters: 277,708Meter age range: 0-20 yearsDone some amount of study to categorize the real or physical losses such as systems loss.Has not undertaken a comprehensive study in the levels of apparent loss arising from inefficiencies in measuring the volume of water consumed by its customers. Literature ReviewFor many years, utilities and water professional researchers have been trying to determine the optimum time for meter replacement with no conclusive answer.

Nominally, most water utilities have used a range of service between 10 and 20 years for meter replacement due to the perception of decreasing meter accuracy with length of service

(Davis 2005)

Literature ReviewGenerally Litterature Review highlights theses problems:

The wearing of meter measurement components over time.The accumulation of sediments and scales from lime deposit.Orientation in installation. Impurities in the water (Quality)Inappropriate sizing of metersLiterature ReviewWhile real losses are physical losses and a cost to the water utility, apparent losses are not physical but financial losses.

WHY? . because the product was delivered to the customer but not accurately measured.

(Julian et al. (2008) (Fantozzi, Criminisi, Fontanazza, Freni, & Lambert,2003)Literature ReviewSignificant Study

With the age of the meter kept constant at 10 yrs) .substantial decrease in accuracy with increasing cumulative volume appears to be the primary factor that ultimately drives the need for meter replacement. (Davis 2005)Problem StatementThe volumetric measurement of water consumption by customers of the Water Utility is an issue that requires serious policies and standards. Such policy will involve changing water meters that has outdone their useful life based on established guideline.

The level of apparent water loss by meter inaccuracy is not known and therefore the company cannot make decisions based on a cost benefit analysis. Purpose of the StudyThe purpose of this study is to examine the effects of aging meters and their inaccuracies on the revenue of the Water Utility. .

Theoretical FrameworkLike any machinery, potable water meters lose their efficiency over time.

It is estimated that within a six year time span, registration errors (under-registration) due to loss in efficiency ranges from 3-10%. (Farley & Trow, 2003, p.7).

Meter Types

Single JetMulti Jet

Nutating Disc

ADVANTAGEGood at low flow

DISADVANTAGEAffected by suspended solidsLarger and heavier than equivalent metersMore expensive than equivalent meters

https://video.search.yahoo.com/search/video;_ylt=A2KLqIUFzxRTQREA0nP7w8QF;_ylu=X3oDMTBrcXU2aHFlBHNlYwNzZWFyY2gEdnRpZANWMTQ5?p=multi+jet+water+meter+principle&ei=utf-8&fr=yfp-t-901Meter TypesCaCo2 Deposit Meter Accuracy

1/8 inch depositWhat Pairs are SayingArregui et al. (2006) therefore indicated that the metering errors at low flow rates are higher than errors at high flow rates.

According to Arregui et al. (2006) findings, the metering errors for volumetric meters will only tend to go negative as the age or cumulative flow becomes greater. Meter Decay with Cumulative Volume

Typical Decay Error Curve

Adapted from Arregui, Cabrera and Cobacho, 2006, Integrated Water Meter Management, p. 140Research QuestionWhat is the economic age for the replacement of water meters?

What revenue loss is incurred through aged meters?

Limitations

Company does not remove meters for sample testing.

Difficult to determine whether it was installed as a new meter or a retrofitted one.

Poor data integrity ; difficulty ascertaining the age of the metersInstrumentMeters were tested using a fixed meter test bench (calibrated to the American Water Works Association (AWWA) standards)

Procedure..

Instrument

TESTQmin, Qt and Qmaxmaximum admissible error narrows from +/- 2 % to +/- 5%

Low Flow (Qmin) gal. per minute (gpm) or 59.5 L/hrTransition Flow (Qt) 2 gal. per minute (gpm) or 477 L/hrMaximum Flow (Qmax) 20 gal. per minute (gpm) or 4,542 L/hr

Research DesignDependent variable (meter accuracy)Independent variable (meter age).

Subsequently changed to cumulative volume as a representation of the age of each meter.

For this research, the samples for testing was taken from a surface water supplyModels TestedSR SR2 T10RESULTS

27Typical Results from Research InvestigationResults

The overall results of all (131) the meter tested were analyzed using the software, Statistical Programme for Social Science (SPSS).

The percentage under registration at each test level along with the cumulative volume for each meter were entered into the SPSS database for processing of the following statistical analysesResultsBrand MeterPercentage FailureLow FlowMedium FlowHigh FlowAll Brands68.717.5610.69Qmin.Qt.QmaxSensus SR63168Sensus SR22044Neptune T10742TOTAL 902414Number of Meters that Failed the AWWA Test Standard

31% Under registration rangeFlow Rate/number of meterQminQtQmax0-10306410210-20175320-30130130-4071040-5030050-6020060-7000070-8020080-9050090-1002300Number of meters that inaccurately over registered144610Failure by percentage range

SRTest LevelSample SizeMinimumMaximumMeanStandard DeviationLow flow64-105.1199.60-58.5442.94Test LevelSample SizeMinimumMaximumMeanStandard DeviationLow flow43-100.001.00-29.9037.42T10Test LevelSample SizeMinimumMaximumMeanStandard DeviationLow flow24-100.000.50-22.1736.42SR2DescriptivesNMinimum error (%)Maximum error (%)Meanerror (%)Standard DeviationQmin.116-99.999.6-34.988539.7717Qt.116-39.9510.23-1.38794.8535Qmax.116-20.578.24-1.84992.8923Cumulative volume (L)11635,22510,000,0002,365,9932,080,544Valid N (Listwise)116Correlation AnalysisCorrelation CoefficientQminQtQmaxAll meters (131)-0.303**-0.039-0.072Failed meters removed (83)-0.118-0.010-0.266*Correlation Coefficient by ModelSR -0.504 after Failed meter removal 0.746

SR2 -0.146 after Failed meter removal -0.593**

T10 -0.017 after Failed meter removal -0.01736SR Model

SR2 Model

T10 Model

Number of Meters Within the Company that has Cumulative meter reading exceeding 500,000 litres

Research Question 1.

What is the economic age for the replacement of water meters?

NB Meter with lowest recorded cumulative volume failed all three testResearch Question 1.

Cumulative volume rather than age will be the recommendation for determining the replacement

From study(81 or 62%) had recorded volumes lying within the 500,000 to 1,000,000 litre range.

ResultsAverage Cumulative FlowPossible Error of each model SR2,756,760.4422.18%SR21,487,006.4211.36 %T103,188,524.469.58%Research Question 1.

A conservative recommendation would be to replace meters that has recorded

Estimated number of years based on 23,000 litres per month average usage.

ModelRecommended Cumulative Volume Threshold (litres)Average Annual Usage (litres)Estimated no of YearsSR2,700,000.00 272,760.00 9.90 ->10SR21,500,000.00 272,760.00 5.50 -> 6T103,000,000.00 272,760.00 11.00 ->1145Research question 2:What revenue loss is incurred through aged meters?

There are 2155 meters that has exceeded the 1 million litre mark in their service life.

Assuming that all these are SR2s (most dominant in the field). Research question 2:What possible revenue loss is incurred through aged meters?

23000 x 2,155 = 49,565,000 Litres/monthEstimating an 11.36% loss.The true volume = 1.1136 x 49,565,000 = 55,195,584 Litres

Estimated Apparent Loss through meter error= 6,352,193L

Estimated Revenue loss at 32cents/litre = $2,032,701.81/mth or $24,392,421.66 annuallyResearch question 2:ROICurrent average replacement cost of a domestic meter is $8,260.00. Average monthly domestic revenue is approximately $7,950.00ROI for the average customer would be approximately one monthConclusionThe general results for all three models indicate that all the meters tested were least efficient in their performance at the low flow range.

The T10 model is the most reliable The SR model is the least performing meter

RecommendationsImplement a meter replacement policy using cumulative volumetric threshold as the basis for replacement.

Further cross sectional studies will be necessary to discover other interesting dynamics such as:

CaCo2 levels in each supply zoneResearch the effects based surface vs undeground supply. Indirect supply via storage tanks that are sucseptable to low flowConsider Investing more in the T10 model

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