Thames desalination plant has supplied just seven days' water at a cost of £500m

London's desalination plant has cost more than half a billion pounds since 2010 and has run only five times, delivering 7.2bn litres of drinking water, approximately seven days of London's typical daily demand.

- Rachel Salvidge

Now Thames Water is planning a new £500m project to tackle drought in the capital.

The Thames Gateway desalination plant at Beckton, built for £270m and now largely mothballed, has racked up an estimated £200m in debt interest, about £45m in idle upkeep and about £3m in operating costs, according to Thames Water figures. That puts the lifetime bill at about £518m, or about 7p for every litre the plant has ever produced, which is 28 times more than customers usually pay for their water.

Thames Water now plans to build a new drought-resilience scheme for an estimated cost of £359m-£535m which will be paid for by customers.

The Teddington Direct River Abstraction (TDRA) scheme would remove water from the river at Teddington, southwest London, pump it to the Lee valley reservoirs in north London, and replace it with treated effluent from Mogden sewage works in west London.