The large operational Water Treatment Works, owned by Thames Water, is between the Upper Sunbury Road (A308) and the River Thames. The works occupy an area of 66 ha and supplies about 30 per cent of London's mains water. It was built in the 1850s after the 1852 Metropolis Water Act made it illegal to take drinking water from the tidal Thames below Teddington Lock because of the amount of sewage in the tidal river. The works were designed by Joseph Quick and initially comprised sand filter beds to remove suspended solids from the river water and three pump houses on Upper Sunbury Road for three water companies — the Grand Junction Waterworks Company, the Southwark and Vauxhall Waterworks Company, and the West Middlesex Waterworks Company. The companies built additional filtration, water storage and steam driven pumping plant until 1902 when they were amalgamated into the Metropolitan Water Board. The Board continued to develop new facilities at Hampton. The site includes Victorian buildings, filter beds and some larger water storage beds.  