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Evaluating W ater Losses 77

regulations. The American Water Works Association (AWWA) Water Loss Control Com-
mittee (WLCC) has adopted the IWA water audit methodology and performance indi-
cators as best practice in its committee report “Applying Worldwide Best Management
Practices in Water Loss Control” published in the August 2003 edition of the AWWA
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Journal. The AWWA WLCC is currently in the process of rewriting the AWWA M36
manual of “Water Supply Practices, Water Audits, and Leak Detection” to incorporate
the current best practice for water audits and in general water loss management. In
addition the World Bank, the Asian Development Bank, and the European Investment
Bank have also adopted the IWA methodology as best practice to assess water losses
and determine performance indicators.
The water audit discussed in this chapter relates to the treated water distribution
network and does not include the raw water transmission systems or the treatment
process. The reason is that in the majority of systems the losses stemming from the dis-
tribution system represent an order of magnitude that eclipse the losses stemming from
the raw water transmission systems or the treatment process. However, water losses
from the raw water transmission system or the treatment process can be evaluated in a
separate balance if necessary.

7.2 A Rosetta Stone for Water Loss Measurement
In 1799, Napoleon’s soldiers found an ancient carved piece of black basalt at Rosetta,
near the mouth of the river Nile. It contained a decree of the Egyptian priests of Ptolemy
V. Epihanes (205–181 BC) written in Egyptian hieroglyphics, demotic characters, and
Greek, permitting a simultaneous translation of these three written texts. The Rosetta
stone enabled the hieroglyphics to be correctly translated for the first time by archae-
ologists.
This could have more to do with water loss accounting in North America than the
reader may at first imagine. Remarkably, in North America, there is no single standard
terminology, or commonly accepted definitions or methodology for undertaking an
annual water audit of the components of a water balance. The water balance calculation
seeks to identify the destinations of all water entering a distribution system, so that the
water losses occurring within the distribution system can be assessed. Each state, gov-
ernment organization, professional institution, consultant, or contractor can (and usu-
ally does!) define the terminology and undertake the calculations in any way they please.
This is perhaps because few states request or require water utilities to report such data
on an annual basis. However, water is an important natural resource, and in an increas-
ing number of developed countries similar absences of accountability for demonstrating
responsible stewardship of natural resources is being actively addressed.
For example, in England and Wales, since 1992 the privatized water companies
have had to produce annual independently audited calculations of water losses in a
standard format, for national publication by their economic regulator. Publication of
standardized data raised questions regarding performance and economic levels of
water losses, which in turn (spurred by the 1995–96 drought and political impetus)
resulted first in voluntary, and then mandatory, leakage targets. Some 5 years later,
leakage from public water supply systems in England and Wales has been reduced
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overall by 40%, or some 480 mgd, and U.K. expertise in modern leakage management
is now internationally recognized. Would any of this happened had the English and
Welsh water utilities been permitted to choose for themselves: