Ruislip Reservoir History

Ruislip Reservoir Post Card 15
What we know today as Ruislip Lido started life as Ruislip Reservoir in the early 1800s. The reservoir was constructed primarily as a feeder for the Grand Junction Canal Company (GJCC) to supply water to their canal at Hayes, some seven miles from the Lido.

As part of the Ruislip Enclosure from 1804 to 1814, large areas of land in the old parish of Ruislip were divided up and fenced by Act of Parliament. Most of the land in the parish until then had been open fields and common grazing. To pay the cost of organising these enclosures, some portions were sold, and one lot was purchased by the GJCC.

The area now occupied by the Lido was formerly just dry scrubland set in a shallow valley. The hamlet of Park Hearne, consisting of seven half-timbered cottages and their enclosures stood on the bank of the stream near the southern end of the valley. Despite strong resistance from some of the cottage owners, by 1807 the company possessed all of the land required for construction to proceed on the reservoir, although it was to be nearly three years until construction began, due to the company's finances being constrained at this time.

The reservoir would be formed by damming the stream that ran across the valley and would then be filled by small feeder streams from Copse Wood and from what is now Northwood Golf Course. When the time came it is alleged that the military had to be brought out from Windsor to evict the residents from the cottages as with the dam nearing completion, the reservoir began to fill. The foundations of those cottages still remain below the Lido today, although the rumours of complete buildings extant under the waters are just a myth.

Although John Rennie was appointed as consultant engineer, the day-to-day supervision of the works at Ruislip was conducted by William Anderson, a Scotsman, who had been working with John Rennie since 1800. Hugh Mackintosh was the primary contractor. On 5th December 1811 the project was announced as complete by Rennie – despite the nay-saying of detractors, fears of the reservoir leaking due to a sandy bed were not founded.

With the reservoir being situated some seven miles from the canal, a feeder channel was required to carry the water. Exiting the reservoir in the south-west corner of the dam, the water entering the feeder fell initially in a large tunnel, dropping down the considerable distance to the valley floor behind the dam, before starting its journey out towards Bury Street.

After a considerable delay due to various problems encountered with construction, mostly with landowners along the route, the feeder was finally completed in June 1816. A legacy of the wrangles over construction was that the feeder took an indirect route nearly eight miles long to reach the canal by Hayes Bridge.

In the meantime, in August 1814 water mill owners agreed to allow the canal company to draw water from the nearby River Colne, provided an equal amount was then returned to the river from the reservoir via the new feeder. When finally the feeder was completed and water started to flow it proved to be of very poor quality, the local floodwater from various sources which filled the reservoir contaminated both the canal and local drinking water supplies, causing constant complaints.

The GJCC struggled on with use the reservoir as a source of supply until 1826 when it changed to the Thames at Chelsea as a source of supply. The Regent’s Canal Company took over the reservoir in 1827, having opened their canal in 1820, and is thereafter shown as the occupier of the reservoir and feeder in Ruislip Parish rate books, with the GJCC as owner.

However, the reservoir was no longer in use, having instead become an expensive white elephant. The full length of the feeder no longer exists, although most of the route can still be traced on foot today. Water flowing out of the reservoir now instead is diverted into the Cannon Brook; the route it took prior to construction of the dam.


I am grateful to Chris Ladyman for this piece, Chris works tirelessly for The Ruislip Lido Railway