Wraysbury Reservoir from the air, looking south
|Basin countries||United Kingdom|
|Surface area||2.05 square kilometres (0.79 sq mi)|
|Water volume||34 Gl (7.5×109 imp gal)|
The Wraysbury Reservoir is a water supply reservoir for London lying just west of the M25 near the village of Wraysbury. The reservoir was begun in 1967 and completed in 1970 with a capacity of 34,000 million litres. 
The reservoir is owned and operated by Thames Water and 400 million litres of water are pumped daily from an inlet at Datchet on the River Thames. A neighbouring reservoir is the King George VI Reservoir, opened in 1947, which is supplied from Hythe End. To keep grass on the reservoir short and make inspections easier, Thames Water maintains a flock of sheep on the earthen banks.
Its citation reads:
[It] regularly supports nationally important numbers of wintering cormorant Phalacrocorax carbo, great crested grebe Podiceps cristatus and shoveler Anas clypeata...[It] is an artificially embanked reservoir constructed around 1970. The reservoir also support notable numbers of wintering gadwall Anas strepera.