<P> Water supply and sanitation in London is provided by a number of 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 . Greater London is located within the Thames River Basin District . </P> <P> Water supply by population </P> <P> 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 . </P> <P> Greater London is currently supplied by four companies: Thames Water (76% of population), Affinity Water (14%), Essex and Suffolk Water (6.6%) and SES Water (3.4%). </P>

Where does tap water in london come from