Knight Reservoir

In 1898 the Southwark and Vauxhall Waterworks Company operated a water works at Hampton, Middlesex. To increase the raw water storage capacity the company sought legal powers to construct two reservoirs across the river from the Hampton works.{{Cite web|title=Walton Reservoirs|url=http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1315|access-date=23 June 2020|website=Engineering Timelines}} This was achieved through the provisions of the Southwark and Vauxhall Water Act 1898 (61 & 62 Vict. c. cxv){{Cite web|date=1898|title=Southwark and Vauxhall Water Act 1898|url=https://www.legislation.gov.uk/changes/chron-tables/local/111|access-date=23 June 2020|website=legislation.gov.uk}} which empowered the company to build two storage reservoirs; an intake from the river Thames; a pump house, and filter beds. Work began in 1898 on the site of an old mansion called Apps Court.

Construction was incomplete when, in 1902, the Metropolitan Water Board (MWB) was formed under the terms of the Metropolitan Water Act 1902 (2 Edw. 7. c.41). The MWB took over the assets of several companies including the Southwark and Vauxhall Waterworks Company and the partly built reservoirs at Walton.

The MWB continued the construction and the reservoirs were inaugurated in 1907.

The Knight and Bessborough reservoirs have a combined area of {{convert|125.5|acre|km2}} and hold 1,198 million gallons.[http://www.moleseyhistory.co.uk/books/surrey/industrialHistory/index.html#D1 A Guide to the Industrial Archaeology of the Borough of Elmbridge] Other key details of the reservoirs are as follows.

The embankment walls of the reservoirs have a puddle clay core extending down to the underlying blue London clay.

The inlet pipes and water discharge tower are adjacent to the north embankment.

Water from the reservoirs was piped under the river and flowed by gravity to the filter beds at Hampton Water Works.

The Metropolitan Water Board operated the reservoirs until the Board was abolished in 1974 under the provisions of the Water Act 1973 (c. 37).{{Cite web|date=1973|title=Water Act 1973|url=https://www.legislation.gov.uk/ukpga/1973/37/contents/enacted|access-date=23 June 2020|website=legislation.co.uk}} Ownership and control was transferred to the Thames Water Authority (TWA). The water supply industry was privatised in 1989,{{Cite web|date=1989|title=Water Act 1989|url=http://www.legislation.gov.uk/ukpga/1989/15/contents/enacted|access-date=24 Jun 2020|website=legislation.gov.uk}} and the TWA became Thames Water.

Knight and Bessborough Reservoirs are a Site of Special Scientific Interest.

Water was abstracted from the river Thames through an open intake channel (139 m long, 6.7 m wide, with a water depth of 2.4 m) and pumped into the reservoirs.{{Cite web|title=Walton Pumping Station|url=http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1316|access-date=23 June 2020|website=Engineering Timelines}} There were four lift pumps which were originally driven by triple-expansion steam engines each rated at 373 kW at 135 rpm. Each engine was coupled to a two-stage centrifugal pump capable of delivering 114 million litres/day. The reservoirs allowed some settlement of suspended solids, biological cleaning through exposure to sunlight, and provided a buffer storage volume to maintain capacity at times of low flow in the river.

The water quality changes which took place during reservoir storage are as follows.{{Cite book |last=Water Research Centre |title=Water Purification in the EEC |publisher=Pergamon |year=1977 |isbn=0080212255 |location=Oxford |pages=373}}

As originally conceived water from the reservoirs was piped under the river and flowed by gravity to the filter beds at Hampton Water Works. The difference in level between the reservoirs and the filter beds was 9.7 m. The flow of water drove three hydraulic turbines coupled to centrifugal pumps which were used to lift river water into the reservoirs. In addition to the Knight and Bessborough reservoirs there were four smaller rectangular reservoirs (each 750 ft by 550 ft, 229 m by 167 m) located east of the intake channel.Ordnance Survey 25-inch Surrey XII.1 (Sunbury; Walton Upon Thames) Revised: 1912

In the 1920s a water treatment works was constructed to the north of the reservoirs. By 1933 this comprised six slow sand filters (each 220 ft by 170 ft, 67 m by 52 m) located west of the intake channel.Ordnance Survey 6-inch Surrey XII.NW (includes: East Molesey; Esher; Walton upon Thames; West Molesey.) Revised: 1938

In 1926 the steam engines were converted to single cylinder triple expansion steam pumps and steam turbines. Further filter beds were added in 1950 west of the pump house.

Further plant was added as the demand for water grew, and when the Queen Elizabeth II reservoir was commissioned in 1962. The steam engines were replaced with electric motors in 1964.

• London water supply infrastructure
• Walton water treatment works

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{{Thames Water}}

{{Elmbridge}}

{{Hydrology of Surrey}}

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Category:Reservoirs in Surrey

Category:Borough of Elmbridge

Category:Sites of Special Scientific Interest in Surrey

Category:Thames Water reservoirs

Category:Drinking water reservoirs in England

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