Hampstead Heath has around 30 ponds which are fed by natural springs – some are man-made including those of the Hampstead and Highgate chains.
There are two major streams, separated by Parliament Hill which feed the two chains of ponds. The stream to the west has a source near the Vale of Health and supplies water to the Hampstead chain, while the eastern stream has a source near Kenwood and supplies the Highgate chain.The two streams meet north of Camden to form the Fleet river which flows through London to join the Thames at Blackfriars. Originally the streams and the river were above ground but today the Fleet is culverted through sewer pipes.
In 1544 the London Conduit Act allowed the City to make use of “dyvers great and plentiful sprynges at Hampstead Heath” and gave the City general powers to collect water within five miles of the City. In 1589 the City drew up a plan to supply fresh water and also scour the Fleet river which was clogged with rubbish. It’s unclear what this scheme consisted of, but we know it failed to scour the Fleet which remained choked with refuse.
It wasn’t for another 100 years that the springs on the Heath were developed further. In 1692, the City leased the springs on Hampstead Heath to the Hampstead Water Company. This company dug the Hampstead Ponds for use as fresh-water reservoirs in the early part of the 18th Century with the Vale of Health Pond being added in 1777. Around the same time, another series of six ponds (the Highgate chain) was made by damming the eastern stream. The Hampstead Water Company supplied water to a large part of north London through wooden pipes made of bored elm trunks. It was taken over by the New River Company in 1859. * In addition, the health giving qualities of the iron-rich springs became sought after and from the early 18th century Hampstead developed as a fashionable spa.
Today the ponds are no longer used to supply drinking water, but three of the ponds are classed as reservoirs due to the volume of water they hold. This includes Hampstead No. 1 Pond, Highgate Men’s Bathing Pond and Model Boating Pond. It is because of this classification that they must fulfill safety requirements set out by the 1975 Reservoirs Act. The ponds today provide recreation in the form of swimming, angling, and model boating. They also provide stunning views and are a key part of the Heath’s much-loved landscape.
* Farmer, Alan – Hampstead Heath pp12-16