Page 121 - Water Loss Control

CHAPTER 9

Identifying Economic

Interventions against

Water Losses

David Pearson
Stuart Trow

9.1 Introduction
The level of losses from water systems is often considered by observers from outside
the industry to be unacceptable. In many countries, environmentalists and regulators
have expressed concerns at the level of losses, and believe that lower levels should be
achievable. However, any water company has to work within current operating bud-
gets and seek additional finance if these are not sufficient. Leakage control can be
expensive, and water companies will seek to achieve an economic balance between the
costs of leakage control and the benefits that accrue. This balance between costs and
benefits is common in many fields, and the idea of the economic level of operation is
commonplace in many industries. The concept of an economic level of leakage (ELL)
dates back several decades, and there have been many previous attempts to determine
a practical definition and methodology. Previous methodologies tended to confuse the
impact of the various leakage management options available. It is only over the past
15 years that we now have a better understanding of all the issues.

9.2 Definition
Looking at economic theory, there are two levels at which the economic level can be
considered. Taking manufacturing as an example, production can increase by taking on
more labour. Increased costs would be incurred in terms of labour costs, raw material
costs, and costs of production—typically power, which are a function of the level of
production. As levels of production are increased, for example, by increasing the num-
ber of shifts, production will rise until the capacity of the production plant itself becomes
a limiting factor. At some point it may be more economic to extend the plant. However,

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