In the 13th century the population of London had so much increased that the supply of water from wells had become inadequate and liable to contamination, and it had become necessary to seek for fresh sources of supply outside the City area.
The western suburbs and surrounding villages were rich in streams and wells, and it was arranged about 1237 to bring a supply of water in pipes of wood from Tyburn to the City. In the 15th century a further supply was obtained from Paddington.
For the purpose of conserving this supply and making it available for public use, conduits and cisterns were established at suitable points in the City to which the citizens could have access, and bequests were frequently made by the citizens in later times towards the repair and maintenance of these conduits.
Besides the conduits and waterworks, the City was also until a recent period supplied with water from springs, and Strype mentions, as being especially excellent, pumps at St. Martin's Outwick ; near St. Antholin's Church ; in St. Paul's Churchyard and at Christ's Hospital.
Many of the conduits described by Stow had been removed before 1720, as being a hindrance to traffic, viz.: The Great Conduit at the east end of Cheapside ; The Tun upon Cornhill ; The Standard in Cheapside ; The Little Conduit at the west end of Cheapside ; The Conduit in Fleet Street ; The Conduit in Gracechurch Street ; The small Conduit at the Stocks Market ; The Conduit at Dowgate.