Publisher's Synopsis
A comprehensive literature search was done on all aspects of water loss management. Standardization of water loss accounting was desirable due to widely varying reporting and evaluation methods prevalent in North America. The International Water Association's Manual of Best Practice Performance Indicators for Water Supply Services (2000) was the most valuable method of water loss accounting. However, some minor modifications of the methodology were necessary for North American utilities.
The research also found that there was no simple, standardized methodology for analyzing the economic level of leakage (ELL), but several good methods are described in detail in the report. A slightly modified IWA methodology for water loss accounting is presented, with each component of the water balance accompanied with a comprehensive definition. This ensures water balances created using this process have comparable results. Due to the widely varying definitions of "unaccounted-for water," it is strongly recommended that use of this term cease. The report strongly recommends against the use of the percentage of system input performance indicator for the management of real losses. This is because this indicator is highly influenced by the volume of consumption, which is not related to real loss volumes.
A range of new performance indicators is recommended. A critical performance indicator is recommended in the Infrastructure Leakage Index (ILL). The ILI is the ratio of current annual real losses to unavoidable annual real losses. A volumetric indicator, real losses in gallons per connection per day (or gallons per mile of main per day), is recommended for setting real loss management targets. Another volumetric indicator, gallons per customer per day, is recommended for managing apparent losses.
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