It is immensely frustrating that despite our strenuous efforts to reduce leakage, we have missed our 2005/6 target (Oxford Mail, June 22) We are working flat out to reduce water losses as fast as we can without causing gridlock in London, where leakage is highest.

Outside the capital, in our Thames Valley supply area covering towns such as Banbury, Didcot, Guildford, Newbury, Oxford, Reading, Slough and Swindon, leakage is on a par with the rest of the country.

Many Londoners will know first hand about our accelerating programme to replace 1,000 miles of the oldest pipes by 2009.

We have already replaced 300 miles of pipework in more than 1,500 streets in the oldest, most densely populated areas of the capital, such as Camden, Chiswick, Islington, Kensington & Chelsea, and Westminster.

We are having to make good decades of under-investment a third of the capital's mains date back 150 years or more.

Meanwhile, we continue to fix a leak every six minutes in our 20,000-mile network. If Thames Water did not make a profit, there would be no hope of modernising ageing water and sewer networks.

From 2000-2005, our shareholders funded more than £240m worth of extra leakage investment. This was above and beyond the work allowed for by Ofwat's Price Review and paid for by customers.

Currently, we are investing £500,000 every day to drive leakage down as quickly as possible. Higher charges are needed to fund our £3.1bn investment programme from 2005-2010, but we also have to borrow money to make it happen.

No-one would want to lend us money if we weren't profitable.

RICHARD AYLARD External Affairs and Environment Director Thames Water, Reading