Page 133 - Water Loss Control

Identifying Economic Interventions against W ater Losses 115

• Water production
• Demand management options
• Apparent loss strategies
• Resource development
• Abstraction mitigation
Subject to achieving (at least)

• Security of supply target
• Leakage target
• Water use target
• Apparent loss target
• Carbon footprint target
• All environmental constraints (low flows, habitats, etc.)

9.6 History and Experience

9.6.1 England and Wales
England and Wales (E&W) have a well-developed supply system with over 99% of
properties connected to public water supply networks. Continuous supply is available
24 hours a day with less than 0.02% of premises receiving low pressure (usually taken
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to be less than 15 m) at any time during the year. Only 34% of properties are metered, 20
the rest pay for water based on the value of the house. However the network is of mixed
age with some parts of the network well over 100 years old. There is a small number of
operating companies (less than 25 covering over 20 million properties), which were
privatised in 1989, and there is a strong environmental and economic regulatory regime.
Figures on leakage are reported to the regulators each year and audited by independent
assessors. Every 5 years the companies have to develop business plans for the following
20 years, which include a full engineering assessment of their assets and a financial
model of forecast income and expenditure. This is used to establish the price limits for
the next 5 years. Part of the engineering submission involves the assessment of the eco-
nomic level of leakage and whether this is constrained by headroom or not. Following
the severe drought in 1995–96, leakage levels have been reduced by over a third and
leakage targets are set by the regulator each year based on companies’ assessment of
their ELL. Most companies are operating at or close to their assessed ELL. Several com-
panies are operating at a level that is constrained by headroom.
The assessment of ELL within England and Wales has a long history. Although there
were many papers on ELL, the first national study and report on the topic was published in
1980. This set down a methodology for the assessment of ELL, and it identified the benefits
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of pressure control and sectorization in managing leakage. This led to the implementation
of sectors (DMAs) in most companies in England and Wales. The findings of this report
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were updated by a major national research programme that reported in 1994. This and
subsequent reports have led to greater understanding of the relationship between pressure
and leakage and other activities which allow the construction of models to forecast the