King George VI Reservoir

The King George VI Reservoir sits between Stanwell Moor and Staines upon Thames, south-west of Heathrow, England. It is between Staines Moor and a north-south road abutting the Staines Reservoirs. The reservoir was opened in November 1947 and named after the then reigning monarch George VI. It is owned by Thames Water.

It occupies 350 acres and holds 3,493 million gallons or, per The Times, 4,466 million gallons. The top of its banks are 56 ft above the surrounds. The enclosing bank crest measures 5.23 km. Like its Lower Thames siblings, it is of earthen dam build: a puddled clay lining and embankments from materials excavated on site, particularly ballast . It has been built-up from dry land as the eastern Thames Basin lacked sufficiently watered, largely unpopulated, agriculturally unprized vales to be dammed near to which conveniently coal-supplied treatment works and pipes to London could be built.

Wikipedia