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CHAPTER 2
Water Loss Control: A Topic
of the Twenty-First Century
Reinhard Sturm
Julian Thornton
George Kunkel, P. E.
2.1 How Much Water Are We Losing?
Throughout the world water losses are occurring at both the end-user’s plumbing and
the water supplier’s distribution piping. Water losses are a universal problem and they
do occur in both developed and developing countries.
Water loss is defined as occurring in two fundamental ways:
1. Water lost from the distribution system through leaking pipes, joints, and
fittings; leakage from reservoirs and tanks; reservoir overflows; and improperly
open drains or system blow-offs. These losses have been labeled real losses.
2. Water that is not physically lost but does not generate revenue because of
inaccuracies related to customer metering (under recording customer meters),
consumption data handling errors, or any form of theft or illegal use is referred
to as apparent losses.
The sum of real and apparent losses plus unbilled authorized consumption is
defined as nonrevenue water (NRW) according to the standard International Water
Association (IWA) water balance methodology. 1
The World Bank estimates that the worldwide NRW volume amounts to 12,839 bil-
3
lion gal/year (48.6 billion m /year) (Table 2.1) and that the volume of real losses occur-
ring in developing countries alone is sufficient to
supply approximately 200 million people. The mon-
etary value of the global annual NRW volume was
estimated by the World Bank to amount to $14.6 bil- Did you know that the world-
2
lion U.S. per year. The World Bank states in its report wide volume of NRW is approx-
that a high NRW level is normally a surrogate for a imately 12,893 billion gal?
poorly run water utility that lacks the governance,
5
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