Queen Mary Reservoir

From Wikishire
Jump to: navigation, search
Queen Mary Reservoir in 2011

The Queen Mary Reservoir in Middlesex is one of the largest of London's reservoirs supplying fresh water to the metropolis. The reservoir covers 707 acres and is 45 ft above the surrounding area.


Queen Mary Reservoir is located south of Ashford and east of Laleham. It lies south of the A308 and at its closest point ¼ mile north-west of the M3 motorway. Heathrow airport is just under four miles north of the reservoir.


Construction of the Littleton Reservoir was authorised under the provisions of the Metropolitan Water Board (Various Powers) Act 1921 (11 & 12 Geo. 5, c.cxv).[1] It was designed by the Board’s Chief Engineer Henry Stilgoe (1867-1943)[2] and was completed in December 1924.[3] Some sources state that the reservoir was designed by John Watson Gibson for the Metropolitan Water Board.[4][5] It was formally opened by King George V in June 1925 as the Queen Mary Reservoir, renamed for the Queen Consort, Mary of Teck; a plaque commemorates the event.[4] It was the largest reservoir in the world at that time.

In 1943, during World War II, the reservoir was used for testing submersibles. The submersible was nicknamed "Sleeping Beauty". In 2010 Prince Philip visited the reservoir to unveil a modern replica of the submersibles tested here. The model is on display at the Eden Camp museum near Malton in Yorkshire.


The reservoir embankment has a puddle-clay core extending down into the underlying London Clay and gravel/earth shoulders at a slope of 1 in 3.[6] The top of the embankment is 40 ft above the surrounding land. The key engineering parameters are:[6]

Queen Mary Reservoir
Parameter Value
Maximum embankment height 40 ft
Length of Embankment Four miles
Total capacity 40 million cubic yards
Surface area 707 acres
Inflow capacity 1 million cu. yd/d
Emergency drawdown 2 ft 6 in within 24hrs

The reservoir has a ⅔-mile central gravel/earth embankment breakwater running north-south and designed to reduce wave action.[3]


Water is abstracted from the River Thames downstream of Penton Hook Weir at up to 200,000,000 gallons[7] and flows via the ¾-mile Laleham Aqueduct to a pumping station (51°24'56.0"N 0°28'36.9"W) at the western embankment of the reservoir. The pumping station lifts water into the reservoir. An outlet tower is located adjacent to the north-east embankment (51°25'17.4"N 0°26'57.1"W). Water is discharged into the Staines Reservoirs Aqueduct which runs round the north of the reservoir to the Kempton Park and Hampton water treatment works.[8]

The Metropolitan Water Board operated the reservoir until the Board was abolished in 1974 under the provisions of the Water Act 1973 (c. 37)[9] ownership and control transferred to the Thames Water Authority. Under the provisions of the Water Act 1989 (c. 15) the Thames Water Authority was privatised as Thames Water.

Sand and gravel were formerly dredged from the reservoir, making the bottom uneven and affecting water circulation.[3] In 2008 Thames Water digitally modelled the bottom to identify high points where aggregates could be removed. Planning approval was given to remove 1¼ million tons of aggregate and two-thirds of the breakwater. This increased the reservoir capacity by 1¼ percent.[3] A jetty and aggregate processing facility was constructed on the west side of the reservoir just north of the intake.

The emergency drawdown rate (the rate at which the water level in the reservoir can be reduced) was about 10 inches/day. Inspections in 2005-07 identified that this was inadequate, and proposed that the drawdown should be 2 ft 6 in/d as defined in the provisions of the Reservoirs Act 1975.[10] This was achieved by installing twin 5 ft 3 in-diameter siphon pipes over the embankment. The valves controlling the outflow are 43 ft high and have a flow capacity of 460 cu. ft/s. The discharge pipes are 275 yds long and discharge into the Laleham Aqueduct, returning water to the Thames.[6]  

The reservoir and the land to the west are designated Sites of Nature Conservation Importance, covering some 360 ha and noted for their varied bird life.

The Queen Mary Sailing Club is a members sailing club on the reservoir. It owns a subsidiary company Queen Mary Sailsports, bringing all training operations "in house".


  1. "Metropolitan Water Board (Various Powers) Act 1921". 1921. https://www.legislation.gov.uk/changes/chron-tables/local/153. Retrieved 20 June 2020. 
  2. Obituary: Henry Edward Stilgoe, 1867-1943", in ICE Journal, Vol.20, pp.202-203, London, June 1943 this states: 'In 1919 he obtained the position of Chief Engineer to the Metropolitan Water Board, where one of his first duties was to prepare a report on the future water-supplies of London, the proposals made in which were embodied in the Act obtained by the Board in 1921 authorizing a number of important extension works, including the Queen Mary reservoir and intake, trunk mains, filtration plant, and pumping-machinery.’
  3. 3.0 3.1 3.2 3.3 "Engineering Timelines - Queen Mary Reservoir". http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1321. Retrieved 20 June 2020. 
  4. 4.0 4.1 "History of the Queen Mary Reservoir - Village Matters". Village Matters. http://www.villagematters.co.uk/sunbury-matters/sunbury-matters-articles/2014/02/history-of-the-queen-mary-reservoir. Retrieved 25 April 2014. 
  5. Gibson’s entry in the Oxford Dictionary of National Biography states: Gibson joined Lord Cowdray's organization (S. Pearson & Son Ltd), working on the construction of both the King George Dock, Hull, and the Metropolitan Water Board's Queen Mary Reservoir at Staines in Middlesex.
  6. 6.0 6.1 6.2 Philpott, Bryn and Yinka Oyeyemi and John Sawyer (June 2009). "Queen Mary and King George V emergency draw down schemes". Dams and Reservoirs 19: 79–84. https://britishdams.org/2008conf/papers/Construction%20remedial%20works%20and%20discontinuance/P%2022%20Oyeyemi%20final.pdf. 
  7. Spelthorne Council A Walk round Laleham village
  8. Ordnance Survey 25-inch map, Middlesex XXIV.4 (Ashford; Littleton; Sunbury) published 1936
  9. "Water Act 1973". https://www.legislation.gov.uk/ukpga/1973/37/contents/enacted. Retrieved 21 June 2020. 
  10. "Reservoirs Act 1975". 1975. http://www.legislation.gov.uk/ukpga/1975/23/contents/enacted. Retrieved 20 June 2020. 

Outside links