A huge underground water reservoir in Enfield has been drained for its 10-year inspection revealing this usually hidden space for a short time. Draining and inspecting underground reservoirs is required by law every 10 years so engineers can carry out any necessary work to maintain water quality standards.
Built in 1976, Cockfosters Service Reservoir next to Trent Park in Enfield holds more than 81 million litres – about 30 times more than an Olympic swimming pool – of treated water before it is pumped to the taps of 30,000 properties in north-west London. Next to Trent Park, it covers an area bigger than a football pitch and is almost seven metres deep.
Thames Water engineers have been designated as key workers during the coronavirus outbreak to help ensure the taps and toilets of millions of customers continue to work. However non-essential work, such as meter readings, has been reduced.
Cockfosters Service Reservoir comprises two ‘cells’ so, while one is drained for inspections, the other can continue to supply water to local people.
Thames Water has approximately 320 service reservoirs and 520 individual cells on an inspection programme, and typically inspects 60 cells per year.