Water UK, the body which represents the UK water and wastewater companies at national and international level, has issued a statement clarifying what it regards as confusion about how leakage performance is measured.

Water UK has also defended the sector’s record on leakage, saying that six of the ten water and sewerage companies achieved their lowest ever leakage levels in 2012-13. The other four all achieved their second lowest levels in that year, having achieved their lowest ever levels in the previous year. 

Of the nine water only companies, five achieved their lowest ever leakage levels in 2012-13. The other four all achieved their second lowest levels in that year, having achieved their lowest ever levels in the previous year.

The statement says that the overall trend in leakage in England and Wales over the past 10 years has been continuously downward.

Commenting on how leakage performance is measured, Water UK said that neither the UK water companies nor the industry regulators used percentage of total supply as a measure of leakage performance, describing it as “almost always misleading.”

The statement says that all the companies have made efforts to reduce both leakage and customer demand in recent years but points out that if demand is reduced proportionately by more than leakage, then leakage in percentage terms could rise, even though both parameters have decreased.

Water UK said there was no reason why leakage should relate to the total quantity of water supplied into the network and that leakage levels depend on the condition of the pipes, the pressures in the network and the efforts made by the companies to manage leakage operationally, not on the volume produced. The statement says:

“Leakage as a percentage of total production is not only misleading, it is irrelevant. The only appropriate measure of trends in leakage performance is the total volume of losses in megalitres per day (Ml/d).”

The total annual leakage levels in England and Wales in the last three years were as follows:

• 2010-11: 3365 Ml/d
• 2011-12: 3108 Ml/d
• 2012-13: 3097 Ml/d

According to a Utility Week analysis published last week of water company data submitted to Ofwat, leakage measured as a percentage of overall water delivered rose last year. The publication reported that of the ten water and sewerage companies, all but two recorded a rise in leakage as a percentage of water delivered.