Great Conduit

The Great Conduit was a man-made underground channel in London, England, which brought drinking water from the Tyburn to Cheapside in the City.

[1] In 1237 the City of London acquired the springs of the Tyburn and built a small reservoir, a head of water, to help serve the city with a steady, free, flowing supply.

It then ran along Cheapside (meaning market side, a key retail and general market of the city) where a building housed a great trough/tank and led to a surplus, overflow channel.

Citizens from this were at liberty to draw water in small amounts, and greater for permitted purposes.

[2] In the 15th century further source was added to the main conduit, from the Westbourne, enabling a new, additional off-tap at Cripplegate: one parish within and one without (outside) a northern gate in ancient, sparsely intact walls.

Official, City of London Arms-bearing, dark blue rectangular plaque that reads: The Great Conduit stood in this street providing free water
13th century to 1666
A map depicting Westminster in 1643 which shows plans for Cromwellian walls and forts; and the reservoir in Green Park . The latter was the conduit's source. Its marked the Tyburn's northern mouth, an undrawn, probably no longer, middle mouth of medieval times being south of Westminster Abbey and a further one being near much later Vauxhall Bridge