Page 226 - Water Loss Control

Contr olling Appar ent Losses—Customer Meter Inaccuracy 199

• Turbo (turbine) meters show a loss of registration first at low flows due to bearing
wear. Be certain that testing was performed reliably at the low flow rates.
• Compound and fire line meters have a crossover flow. Take time when testing
to determine this rate. Evaluate each side of crossover as a cause for failure
along with valve problems. Do not attempt to isolate measuring chambers and
conduct isolated tests.
It is important to remain objective when interpreting meter test results. As long as
you are following proper meter testing procedures, let the test results speak for them-
selves. Attempt to discern any anomalies by explaining the function and application of
the meter and be cautious not to quickly dismiss meter test results as poor testing pro-
cedure. Again, rely upon your training and expertise to evaluate and diagnose tested
meters; never stop looking, listening, and learning. Table 12.10 gives a listing of poten-
tial meter problems that can explain variant large meter accuracy test results.
When meter performance is not consistent, the meter should be inspected for any
significant change in the customer water consumption pattern and for any meter mal-
function. Actions to remedy a malfunctioning meter might include: repair the meter
(for large meters greater than 1 in), replace the meter if necessary with consideration to
replacement using a different size meter if necessary. When the performance of a meter
is in doubt, particularly if a meter has been in service for a number of years, it is best to
replace the meter. The meter is the origin of customer consumption data in the water
utility and it is very important that the water utility manager have a high level of con-
fidence in the function and accuracy of the customer meter population.

References
1. American Water Works Association. Manual of Water Supply Practices, Water Audits
and Loss Control Programs (M36). 3rd ed., Denver, Colo.: AWWA, 2008.
2. Davis, S. “Residential Water Meter Replacement Economics.” Leakage 2005 IWA
Conference, Halifax, Nova Scotia, CA, 2005.
3. Sullivan, J. P. and E. M. Speranza. “Proper Meter Sizing for Increased Accountability
and Revenues.” Proceedings, American Water Works Association, Annual Conference &
Exposition: AWWA, 1991.
4. American Water Works Association. Manual of Water Supply Practices, Sizing Water
Service Lines and Meters (M22). Denver, Colo.: AWWA, 2004. ISBN 1-58321-279-5.
5. Arregui, F., E. Cabrera and R. Cobacho, et al. “Key Factors Affecting Water Meter
Accuracy.” Leakage 2005 IWA Conference, Halifax, Nova Scotia, CA, 2005.
6. Grothaus, R. “Size Matters: Meters Can Reflect New Standards.” AWWA Opflow,
March, 2007.
7. Rizzo, A. and J. Cilia. “Quantifying Meter Under-Registration Caused by the Ball
Valves of Roof Tanks (for Indirect Plumbing Systems).” Leakage 2005 IWA Conference,
Halifax, Nova Scotia, CA. 2005.
8. Cohen, D. “UFR (Unmeasured-Flow Reducer): An Innovative Solution for Water
Meter Under-Registration—A Case Study in Jerusalem, Israel.” Global Customer
Metering Summit: London, England. July 2007.
9. American Water Works Association. Manual of Water Supply Practices, Water Meters—
Selection, Installation, Testing, and Maintenance (M6). 4th ed., Denver, Colo.: AWWA,
1999. ISBN 1-58321-017-2.