Water companies report annual leakage figures to Ofwat as part of their annual regulatory returns. Ofwat publishes leakage performance annually in its Service and Delivery report. Ofwat sets the water companies targets to reduce their leakage to the economic level, the level of leakage at which it would cost more to make further reductions than to produce water from another source. Since 1997, total leakage has been reduced by 27 per cent. in England and Wales. All water companies met their leakage targets during 2007-08.
Leakage performance for Severn Trent Water and South Staffordshire Water for the years 2003-04 to 2007-08 was as follows:
2003-04 2004-05 2005-06 2006-07 2007-08 Severn Trent 512 502 540 525 490 South Staffordshire 71 74 73 73 72