Wraysbury Reservoir
Wraysbury Reservoir is a water supply reservoir for London, just west of the M25 near the village of Wraysbury, and directly under the western approach path of Heathrow Airport. The reservoir was begun in 1967 and completed by W. & C. French in 1970 with a capacity of 34,000 million litres.
Engineering design data for the Wraysbury reservoir is as follows.
| Parameter | Value |
| Top water level above ordnance datum | 31.1 m |
| Volume of water storage | 35 million m3 |
| Maximum depth of water | 21 m |
| Water area | 202 ha |
| Maximum height of bank above ground | 17 m |
| Perimeter of bank | 5,700 m |
The reservoir is owned and operated by Thames Water; 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 the grass short and make inspections easier, Thames Water maintains a flock of sheep on the earthen banks.
It is a biological Site of Special Scientific Interest and part of South West London Waterbodies Ramsar site and Special Protection Area. It has nationally important numbers of wintering cormorants, great crested grebe and shovelers. It also supports many gadwalls.