the revenue effect of inefficient potable water meters on a water utility co

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

For 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. 3

Significance of the Study Serve 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 Commission

Water production: 24.09 billion Litres Billed volume: 8.18 billion Litres LOSSES 15.91 billion Litres Leaks, Overflows Theft, Acc. Errors Meter Errors Theft, Acc. Errors Meter Errors Physical Apparent

The Water Company Active Customer base: 334,337 Possessing meters: 277,708 Meter age range: 0-20 years Done 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. Active Customer base: 334,337 Possessing meters: 277,708 Meter age range: 0-20 years Done 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 Review For 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 Review Generally 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 meters

Literature Review While 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 Review Significant 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 Statement The 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 Study The purpose of this study is to examine the effects of aging meters and their inaccuracies on the revenue of the Water Utility..

Theoretical Framework Like 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 Jet Multi Jet Nutating Disc

ADVANTAGE Good at low flow DISADVANTAGE Affected by suspended solids Larger and heavier than equivalent meters More expensive than equivalent meters https://video.search.yahoo.com/search/video;_ylt=A2KLqIUFzxRTQREA0nP7w8QF;_ylu=X3oDMTBrcXU2aHFlBHNlYwNzZWFyY2gEdnRpZA NWMTQ5?p=multi+jet+water+meter+principle&ei=utf-8&fr=yfp-t-901 Meter Types

CaCo2 Deposit Meter Accuracy 1/8 inch deposit

What Pairs are Saying Arregui 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. 140

Research Question What 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 meters

Instrument Meters were tested using a fixed meter test bench (calibrated to the American Water Works Association (AWWA) standards) Procedure..

Instrument

TEST Qmin, Qt and Qmax maximum admissible error narrows from +/- 2 % to +/- 5% Low Flow (Qmin) gal. per minute (gpm) or 59.5 L/hr Transition Flow (Qt) 2 gal. per minute (gpm) or 477 L/hr Maximum Flow (Qmax) 20 gal. per minute (gpm) or 4,542 L/hr

Research Design Dependent 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 supply

Models Tested SR SR2 T10

RESULTS

Typical Results from Research Investigation

Results 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 analyses

Results Brand Meter Percentage Failure Low Flow Medium Flow High Flow All Brands68.717.5610.69

Qmin.Qt.Qmax Sensus SR63168 Sensus SR22044 Neptune T10742 TOTAL 902414 Number of Meters that Failed the AWWA Test Standard

% Under registration range Flow Rate/number of meter QminQtQmax 0-10 30 64102 10-20 17 53 20-30 13 01 30-40 7 10 40-50 3 00 50-60 2 00 60-70 0 00 70-80 2 00 80-90 5 00 90-100 23 00 Number of meters that inaccurately over registered 144610 Failure by percentage range

SR Test Level Sampl e Size MinimumMaximumMean Standard Deviation Low flow 64 -105.1199.60-58.5442.94 Test Level Sample Size MinimumMaximumMean Standard Deviation Low flow43-100.001.00-29.9037.42 T10 Test Level Sample Size MinimumMaximumMean Standard Deviatio n Low flow24-100.000.50-22.1736.42 SR2

Descriptives N Minimum error (%) Maximu m error (%) Mean error (%) Standard Deviation Qmin.116-99.999.6-34.988539.7717 Qt. 116 -39.9510.23-1.38794.8535 Qmax. 116 -20.578.24-1.84992.8923 Cumulative volume (L) 116 35,22510,000,0002,365,9932,080,544 Valid N (Listwise) 116

Correlation Analysis Correlation Coefficient QminQtQmax All meters (131)-0.303**-0.039-0.072 Failed meters removed (83) -0.118-0.010-0.266*

Correlation Coefficient by Model SR -0.504 after Failed meter removal 0.746 SR2 -0.146 after Failed meter removal -0.593** T10 -0.017 after Failed meter removal -0.017

SR 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 test

Research 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.

Results Average Cumulative Flow Possible Error of each model SR2,756,760.4422.18% SR21,487,006.42 11.36 % T103,188,524.46 9.58%

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. Model Recommended Cumulative Volume Threshold (litres) Average Annual Usage (litres) Estimated no of Years SR 2,700,000.00 272,760.00 9.90 ->10 SR2 1,500,000.00 272,760.00 5.50 -> 6 T10 3,000,000.00 272,760.00 11.00 ->11

Research 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/month Estimating 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 annually

Research question 2: ROI Current average replacement cost of a domestic meter is $8,260.00. Average monthly domestic revenue is approximately $7,950.00 ROI for the average customer would be approximately one month

Conclusion The 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

Recommendations Implement 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 zone Research the effects based surface vs undeground supply. Indirect supply via storage tanks that are sucseptable to low flow Consider Investing more in the T10 model

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the revenue effect of inefficient potable water meters on a water utility co

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