Image description: A water glass held up by a hand. Image by Manki Kim on Unsplash.
Thames Water’s desalination plant, officially known as the Thames Gateway, has cost more than half a billion pounds since 2010 and has run only five times. Over 15 years it has delivered 7.2bn litres of drinking water, equating to roughly seven days of London’s typical daily demand. Now Thames Water is planning a new £500m project to tackle drought in the capital, sparking criticism from environmentalists and MPs.
Located in East London, the plant was designed to convert brackish water from the River Thames into potable water using reverse osmosis, with a capacity of up to 100 million litres per day. However, it has been largely inactive since its completion.
Built for £270m the plant has racked up an estimated £200m in debt interest, about £45m in idle upkeep and about £3m in operating costs according to Thames Water figures. A total cost of £518 million, that works out to about 7p per litre, 28 times more than customers usually pay for their water.
Thames Water’s new plan for drought-resilience
Thames Water is currently planning to build a new drought-resilience scheme on the Thames for an estimated cost of between £359-£535m which will be paid for by customers.
The Teddington Direct River Abstraction (TDRA) scheme would remove water from the river at Teddington, pump it to the Lee Valley reservoirs in north London, and replace it with treated effluent from Mogden sewage works in west London.
However, it is argued the Beckton desalination plant is not a clean fix. Negative consequences include it being energy intensive, producing brine and discharging effluent containing chlorine, chloroform and bromoform (disinfectant byproducts) into the Thames. Other waste streams are “chemically neutralised” before being mixed with outflows from the neighbouring Beckton sewage works and released into the river.
Why is the plant not in use?
According to Thames Water the plant is “not currently available” because of “reservoir safety related works”, essential maintenance and because it is awaiting drinking water inspectorate approval for new reverse-osmosis membranes.
However official documents suggest the plant has faced other issues. Repeated chemical leaks have forced workers to wear protective chemical suits to enter parts of the site and Thames Water has admitted that system failures have “prevented the plant from ongoing running due to health and safety issues”.
Upgrades are under way, with the aim of getting 50m litres of water a day [Ml/d] by the end of the current five-year investment cycle and “75Ml/d during drought periods” by 2031, according to the water company’s documents. A Thames Water spokesperson said the Gateway desalination plant is designed to provide up to 5% of London’s supply “during very dry conditions”, with decisions on operation based on long-term forecasts and storage levels. Once safety works and maintenance are complete it will run “in line with our water resources management plan”.