The major demand challenges are in the Essex area, which stretches from Dagenham in East London to Chelmsford. The area has a population of 1.4 million and includes much of the Thames Gateway, earmarked for development under the Deputy Prime Minister's "sustainable communities" plan for boosting homebuilding in the South East.
Ground and surface water supplies in the Essex area provide only 50% of the population's water demand. Some 20% is imported from Thames Water's Lea Valley reservoirs.
The remaining 30% comes from the river Ouse as part of the Ely Ouse to Essex transfer scheme operated by the Environment Agency. This scheme, developed in the 1960s, takes water from the Ouse in Norfolk and transfers it through tunnels and rivers to boost flows in Essex rivers supporting abstractions for the company's two reservoirs at Abberton, near Colchester, and Hanningfield, near Chelmsford.