Page 96 - Water Loss Control

78 Cha pte r Se v e n

• Whether to undertake annual calculations of water losses, or not.
• How the calculation should be carried out and which performance indicators
should be used?
• Whether the results should be published, or not.
The extent of the problem in North America can be illustrated from the results of an
American Water Works Research Foundation (AwwaRF) project titled “Leakage Manage-
ment Technologies,” completed in 2007. The report concludes that although performing
water audits is common in North America, the methods, the expressions of water loss, or
time intervals are not consistent. Most utilities do not use the IWA standard method for
water audits. Many audit methods currently used leave ample room for inaccurate
accounting and measures of performance. In North America, water loss cannot be accu-
rately compared between utilities because water loss is still commonly expressed as a
percentage of system input volume, a practice that allows the denominator (the high per
5
capita consumption of North America) to minimize water loss. The IWA/AWWA stan-
dard water audit methodology and performance indicators are the Rosetta Stone for
water auditing in North America. However, as mentioned in Chap. 4 there have been very
important and encouraging developments in the United States over the past 5 years, with
several state agencies and national organizations adopting and promoting the IWA/
AWWA standardized water audit methodology as best practice.

7.3 The Benefits of the IWA/AWWA Standard Water Audit and
Performance Indicators
Advantages of the IWA/AWWA methodology can be summarized as
• The IWA/AWWA methods are structured to serve as a standard international
best practice methodology and terminology for such calculations, based on the
conclusions of IWA Task Forces on water losses and performance indicators.
• The IWA/AWWA methods question the desirability of the common North
American practice of counting unavoidable water losses and discovered leaks
and overflows as part of authorized consumption.
• A system-specific method for calculating unavoidable real losses is included.
• The IWA/AWWA method counters the deficiencies in the performance
indicators most commonly used in North America—percentage of system input
volume and losses per mile of mains.
• The IWA/AWWA has dropped the term unaccounted for water (UFW) in favour
of nonrevenue water (NRW), because there is no internationally accepted
definition of UFW, and all components of the water audit can be accounted for
using the IWA/AWWA methodology.
• The IWA/AWWA methodology does not leave room for ambiguity. Every type
of water use and loss has an appropriate component in the water balance it is
assigned to, which assures that the results are meaningful and comparable.
• The IWA/AWWA methodology has been successfully applied in numerous
countries and utilitised around the globe.