where does tap water in london come from
River Thames River Lea
title: Water supply and sanitation in London text: Water supply and sanitation in London Water supply and sanitation in London is provided by 32 private companies. The regional water strategy for London is produced by the Greater London Authority. Much of the water supply and sewerage system was constructed during the Victorian era, in light of repeated cholera outbreaks. Greater London is located within the Thames River Basin District. London has well developed water supply infrastructure. Most drinking water consumed in London comes from the River Thames and the River Lea. Approximately 70% of all water supplied to London is taken from the Thames upstream of Teddington Weir. title: London water supply infrastructure text: in 1925, King George VI Reservoir (Stanwellmoor) in 1947 William Girling Reservoir (Lea Valley) in 1951, Queen Elizabeth II Reservoir (Molesey) 1962, Wraysbury Reservoir 1967, and Queen Mother Reservoir (Staines) 1976. The Metropolitan Water Board and other local Water Boards were later combined into the Thames Water Authority, which was later privatized as Thames Water, a state-regulated private company which currently provides London's water supply. Greater London is currently supplied by four companies: Thames Water (76% of population), Affinity Water (14%), Essex and Suffolk Water (6.6%) and Sutton and East Surrey Water (3.7%). Most of London's water comes from non-tidal title: London water supply infrastructure text: London water supply infrastructure London's water supply infrastructure has developed over the centuries in line with the expansion of London. For much of London's history, private companies supplied fresh water to various parts of London from wells, the River Thames and in the three centuries after the construction in 1613 of the New River, the River Lea, which has springs that divert alongside Hertford at an elevation of 40 metres AOD. Further demand prompted new conduits and sources, particularly in the 150 years to 1900 as the Agricultural and Industrial Revolution caused a boom in London's population and housing. A title: Hard water text: Water Inspectorate shows that drinking water in England is generally considered to be 'very hard', with most areas of England, particularly east of a line between the Severn and Tees estuaries, exhibiting above 200 ppm for the calcium carbonate equivalent. Water in London, for example, is mostly obtained from the River Thames and River Lea both of which derive significant proportion of their dry weather flow from springs in limestone and chalk aquifers. Wales, Devon, Cornwall and parts of North-West England are softer water areas, and range from 0 to 200 ppm. In the brewing industry in England and Wales, title: River Lea text: lower Lea remains somewhat polluted, its upper stretch and tributaries, classified as chalk streams, are a major source of drinking water for London. A diversion known as the New River, opened in 1613, abstracts clean water away from the lower stretch of the river for drinking. Its origins in the Chilterns contribute to the extreme hardness (high mineral content) of London tap water. The name of the River Lea was first recorded in the 9th century, although is believed to be much older. Spellings from the Anglo-Saxon period include "Lig(e)an" in 880 and "Lygan" in 895, and in the early