Page 37 - Water Loss Control

CHAPTER 3

Understanding the

Types of Water Losses

Reinhard Sturm
Julian Thornton
George Kunkel, P.E.

3.1 Defining Water Supplier Losses
Understanding the types of water losses and having consistent and clear definitions for
the types of water losses occurring in distribution systems is the first step to be able to
manage the problem of water losses.
Simply stated, the problems of water and revenue losses are 1

• Technical: Not all water supplied by a water utility reaches the customer.
• Financial: Not all of the water that reaches the end user is properly measured or
paid-for.
• Terminology: Standardized definitions of water and revenue losses are essential
to quantify and control the losses.
The International Water Association (IWA) defines two major categories under
which all types of supplier water loss occurrences fall:
• Real losses are the physical escape of water from the distribution system, and
include leakage from pipes, joints, and fittings; leakage from reservoirs and
tanks; and water losses caused by reservoir overflows. Real losses occur prior to
the point of end use.
• Apparent losses are caused by inaccuracies associated with customer metering,
consumption and billing data handling error, assumptions of unmeasured use,
and any form of unauthorized consumption (theft or illegal use).

While these two definitions are distinguished by a stark physical differentiation,
in most cases a dramatic economic difference also exists. Real losses, which are most

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