The Revenue Effect of Inefficient Potable Water Meters on a
Water Utility Co
Slide 2
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
Slide 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
Slide 4
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
Slide 5
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
Slide 6
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.
Slide 7
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)
Slide 8
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
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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)
Slide 10
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)
Slide 11
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.
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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..
Slide 13
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).
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Meter Types Single Jet Multi Jet Nutating Disc
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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
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CaCo2 Deposit Meter Accuracy 1/8 inch deposit
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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.
Slide 18
Meter Decay with Cumulative Volume
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Typical Decay Error Curve Adapted from Arregui, Cabrera and
Cobacho, 2006, Integrated Water Meter Management, p. 140
Slide 20
Research Question What is the economic age for the replacement
of water meters? What revenue loss is incurred through aged
meters?
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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
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Instrument Meters were tested using a fixed meter test bench
(calibrated to the American Water Works Association (AWWA)
standards) Procedure..
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Instrument
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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
Slide 25
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
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Models Tested SR SR2 T10
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RESULTS
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Typical Results from Research Investigation
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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
Slide 30
Results Brand Meter Percentage Failure Low Flow Medium Flow
High Flow All Brands68.717.5610.69
Slide 31
Qmin.Qt.Qmax Sensus SR63168 Sensus SR22044 Neptune T10742 TOTAL
902414 Number of Meters that Failed the AWWA Test Standard
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% 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
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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
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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 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
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SR Model
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SR2 Model
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T10 Model
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Number of Meters Within the Company that has Cumulative meter
reading exceeding 500,000 litres
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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
Slide 43
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.
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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%
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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
Slide 46
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).
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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
Slide 48
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
Slide 49
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
Slide 50
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