Environment Agency Says Thames Water Plan has 'Substantial Risk'

Proposal to pump treated wastewater into the river from Mogden

Mogden Sewage Treatment Works. Picture: Jim Linwood

March 30, 2023

The Environment Agency (EA) has raised concerns about controversial plans to pump the River Thames with treated wastewater. More than 13,700 people have already signed a petition in a bid to stop the scheme going ahead.

The public body called on Thames Water to fix leaks in a new report about the company’s 2024 draft water resources management plan, which aims to tackle future water shortages and boost drinking water supply. It comes as the population grows and the risk of drought caused by climate change rises.

Thames Water put forward a number of schemes in the plan after estimating it will need an extra one billion litres of water a day for customers by 2075. The company said reducing leaks is a foundation of the plan.

But the EA warned the company must justify it is making the right decisions, especially when the proposed schemes “carry substantial risk”.

The EA said alternative schemes would cost more but the company “needs to consider whether the short-term costs are outweighed by better long-term benefits”. It also warned the security of water supply will be at risk if the company does not slash leaks and customer demand for water.

One of the proposed schemes would see millions of litres of water a day taken from the Thames between Teddington Weir and Hampton Court and transferred via an underground tunnel to the Lee Valley reservoirs. Treated wastewater would be moved from Mogden sewage treatment works in Isleworth to replace the water taken from the river.

The EA rejected a version of the scheme in 2019 over concerns about unacceptable impacts on the environment. The EA said Thames Water had reintroduced the scheme and made “substantial improvements”, but it still has reservations about its impact on the environment and long-term viability.

The report says, “Given that the Teddington direct river abstraction has not yet been shown to be feasible or environmentally acceptable, the company should ensure alternatives are progressed. Thames Water should ensure any options selected are resilient, reliable and do not cause any adverse environmental impacts.”

The EA also urged the company to explore how to “substantially reduce leakage” further than the 50per cent reduction target it has set for 2050. It said Thames Water “leaks more water than any other company” and while it welcomed the company’s ambition to reduce leaks, added it “must demonstrate it can deliver its ambition”.

The Teddington scheme has attracted fierce opposition, with a petition against the proposals at more than 13,700 signatures. The petition raises concerns about the impact of the scheme on fish, insects and plants, along with fears the site would be an “eyesore” and fines imposed for breaches of regulations would not be enough to protect the Thames.

An EA spokesperson said, “The whole of the South East is determined as being in serious water stress. 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.

“We require further evidence that the direct river abstraction proposal put forward by Thames Water would not have adverse impacts on the environment, along with proof of its long-term viability in light of climate change.

“We urge Thames Water to produce this evidence as quickly as possible and develop alternative options to ensure that it can deliver a secure supply of water for its customers for the next 25 years and beyond.”

Thames Water said the Teddington scheme is a potential option, along with others including a new reservoir near Abingdon and water transfer from the River Severn to the Thames, and that it would not negatively impact water quality.

The Thames Water spokesperson said, “We’ve worked closely with the Environment Agency throughout the consultation process and in developing the scheme. We are now carefully reviewing their feedback on our draft water resources management plan, including comments regarding proposed river abstraction at Teddington.

“As the scheme is only at the conceptual design stage the precise locations have not been confirmed. If the scheme is taken forward, there will be detailed option appraisal and design work, where we will carry out engagement and consultation with the local community.

“The scheme will not negatively impact the river water quality. The treated wastewater effluent taken from Mogden sewage treatment works would go through an additional stage of treatment to ensure there is no deterioration to the water quality in the river. This would also compensate for the volume of water abstracted from the river.”

The spokesperson said the company had met leakage reduction targets for the last three years, cutting leaks by more than 10pc from 2017/18 levels and aiming for a 50pc reduction by 2050. They added, “Reducing leakage is a priority for us and is one of the foundations of the plan. Even with an ambitious target of halving leakage by 2050 we still need more storage in the future to account for growing population demand and climate change.

“We are repairing over 1,300 leaks per week – whether they are visible or hidden below ground across 20,000 miles of pipes across our network – that’s one leak every 7.5 minutes. We’re also working with our customers to reduce leakage from their water pipes, which make up a third of our total leakage.”

Thames Water said increasingly extreme climate conditions had added extra pressure on its pipes and it is working “around the clock to make improvements” while planning ahead to manage a growing population, changing climate and rising drought risk. The company said it has an “extensive capital programme” to fix more leaks, including spending almost £200m on replacing water mains.

The company added it will spend £1.6billion on its sewage treatment works and sewers over the next two years. It said it has started the £100m upgrade of Mogden sewage treatment works and is increasing sewage treatment capacity at other sites. It has also launched a digital map identifying raw sewage discharges via storm overflows.

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