‘Recycling’ plan aims to replace water from Thames with treated sewage

Thames Water is proposing to draw off tens of millions of litres of water a day from the Thames and replace it with treated effluent from Mogden Sewage Treatment Works in west London, to help tackle water shortages.

It forms part of the company’s draft Water Resources Management Plan (WRMP) to maintain supply and protect the environment, from 2025-2050.

The draft WRMP, required by all water companies, aims to address the threats of a growing population, changing climate and increasing drought risk.

Thames Water states: “The government asked water companies to ensure our water supplies are more resilient to severe drought by 2040. We need an extra 321 million litres of water per day in our area to reinforce our water supplies to be resilient to a one in 500-year drought.”

A spokesperson said: “A significant driver in our WRMP is to improve the environment. We have proposed reducing abstraction from our vulnerable chalk streams and other watercourses to improve flows and the habitats for fish and other wildlife.

“With regards to the new river abstraction at Teddington, highly treated recycled water would be transferred from Mogden Sewage Treatment Works to upstream of Teddington Weir and put into the River Thames.

“Putting recycled water into the Thames above Teddington Weir will ‘compensate’ the river for the additional abstracted water, and protect the environment and wildlife.”

Thames Water said that the Environment Agency had been involved in the development of the proposals included in the WRMP to date.

An Environment Agency spokesperson said: “Climate change and population growth mean we need to take action now to ensure resilient water supplies are available to meet the needs of all users in the future.

“Our work to review Thames Water’s proposals is ongoing and we will submit our views before the consultation closes on 21 March 2023.”

John Bryden, Thames21’s head of improving rivers, said: “It is not acceptable for Thames Water to abstract up to 150 million litres of water a day from the Thames and replace it with treated wastewater. This will increase the pollution load in the river.”

He said that “a serious conversation” was needed about leakage from Thames Water’s assets (estimated at 630 million litres per day). He also called for reduced water consumption by both people and businesses. He said: “Current water uses are too high and incredibly unsustainable.”

Thames Water’s draft WRPM addresses leakage and states: “Pipes are very sensitive to changes in temperature, pressure and their surroundings. They also become more susceptible to leaks as they age. The government has set an ambitious target for us to halve leakage by 2050 and we’re determined to achieve this.”

Earlier this year, the Environment Agency revealed it was investigating discharges of more than two billion litres of raw sewage from Mogden into the surrounding waterways. The equivalent of 800 Olympic-sized swimming pools of raw sewage was released across 48 hours in October 2020. 

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