The site was originally developed as the terminus of the New River, "bringing in a freshe streame of running water" from Hertfordshire.

In 1600 Edmund Colthurst had the idea to bring water from the springs in Hertfordshire and Middlesex to London. Letters Patent were granted by King James I in 1604, and
Colthurst, at his own expense, started to cut a channel from Chadwell Spring. Unfortunately lack of money soon halted these works. In 1606 a Parliamentary Act granted the Corporation of London the power to make a “New River for bringing water to London from Chadwell and Amwell in Hertfordshire”.

It fell to Sir Hugh Myddelton to complete the work between 1609 and its official opening on 29 September 1613. The New River Company was founded with the assistance of Sir John Backhouse. The Company's first reservoir was built on his land in Islington. Myddelton gave some of the shares in the New River Company to Colthurst.

The expense and engineering challenges of the project - it relied on gravity to allow the water to flow, carefully following the contours of the terrain from Ware into London, and dropping around just 8 cm per kilometre - were not Myddelton's only worries. He also faced considerable opposition from landowners who feared that the New River would reduce the value of their farmland (they argued that floods or overflowing might create quagmires that could trap livestock); others were concerned at the possible disruption to road transport networks between Hertfordshire and the capital. Myddelton, however, was strongly supported by the king, who agreed to pay half the project's expenses in return for a 50% shareholding; such backing quickly silenced the scheme's critics.

When it was originally constructed, long sections, for example around Forty Hall and in Hornsey, wound around the heads of small tributary valleys of the Lea. Other sections of the river, including the one in Harringay, were carried across valleys in wooden aqueducts lined with lead and supported by strong timbers and brick piers.

The channel was cut by 1613 - a civil engineering achievement vital to the development of the metropolis.

The end point was a small reservoir called the Round Pond, situated at an elevation suitable for water to be piped by gravity to houses in the City and surrounding areas. This circular basin was extended and a larger outer reservoir constructed in the early 1700s; these were known as the ‘Inner’ and ‘Outer’ Ponds.

The next door Sadler's Wells theatre used water from the river to flood a large tank to stage an Aquatic Theatre at the beginning of the 19th century.

The water was initially distributed through some 640 km of connecting elm pipes; by 1820 these were replaced with iron pipes.

To begin with New River Head consisted merely of a reservoir, the Round Pond, and a single building known as the Water House. In time it became a comparatively sophisticated complex with outer ponds and associated structures covering seven acres.

The New River flowed in open channel into the site until 1892, when it was put in pipe and covered. In 1946 the water supply to New River Head was truncated at Stoke Newington with the New River ending at the East Reservoir.

The former Metropolitan Water Board offices of 1915–20, which incorporate a fine late seventeenth-century room from the Water House, and the board's water-testing laboratory of 1936–8 were converted into flats in the 1990s. With the construction in 2000–3 of two further blocks of flats, and the landscaping of much of the open space as gardens, including a grass deck over a car-park on what was once a filter bed, the greater part of the site became private and residential.

Since 1992, Thames Water has worked with local people and partners to create a 45 km long-distance footpath that follows the course of the New River, linking the inner city to the open countryside and its source between Hertford and Ware.