A petition to the UK Government is demanding action to stop micropollutants including 'forever chemicals' ending up in the River Thames amid plans to replace up to 75million litres a day during drought with treated wastewater.

Thames Water's plan to ensure London has enough drinking water during times of prolonged dry weather would see huge volumes taken from the Thames above Teddington Weir and transferred along a new pipeline to an existing underground tunnel.

This water would join the Lee Valley reservoirs, ready to become drinking water. It would be replaced with "highly-treated" wastewater via a tunnel from a new 'tertiary treatment' plant at Mogden Sewage Treatment Works.

The project is referred to as Thames Water's Teddington direct river abstraction (TDRA).

So what are the key objections?

Given it's estimated that Thames Water loses around a fifth of the water it supplies through leaks, campaigners say a plan to ensure the supply of drinking water that introduces potential new harms to the environment and humans is the wrong solution.

Save Our Lands And River (SOLAR) says the current proposals do not do enough to filter out micropollutants that are harmful to humans and wildlife.

They want the new treatment plant to meet stricter standards as demanded in EU countries – effectively adding a fourth stage of treatment for wastewater to remove them.

Such pollutants including so-called 'forever chemicals' can be missed during the three-stage, or tertiary, treatment process planned.

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SOLAR has created a petition, which can be viewed and signed on the Government website, demanding that all new wastewater treatment infrastructure meets those higher international standards, to "safeguard people's health, better protect all water bodies and reduce damaging long-term impacts".

The EU's new Urban Wastewater Treatment Directive, which came into force on January 1, 2025, requires treatment plants serving 150,000 or more people to introduce quaternary, or fourth-stage, treatment by 2045 targeting residual micropollutants.

Although a Change.org petition calling for the Thames Water plans to be scrapped has gained more than 33,800 signatures, SOLAR launched a new petition to the Government to demand action at the highest level.

Petitions on the Government website also require a response if they reach 10,000 signatures.

The petition says: "Proposed new schemes built to outdated standards must be stopped as they will continue releasing biological and chemical contaminants, including forever chemicals, harming water bodies, wildlife, and public health.

"They also risk a dramatic increase in customer water bills to pay for expensive and avoidable upgrades."



The River Thames near Ham Lands. (Credit: Charlotte Lillywhite/LDRS)

'Significant detrimental impact' on Thames

Ian McNuff, from SOLAR, told the Local Democracy Reporting Service (LDRS) the results of Thames Water's recent trial of technology proposed for the Teddington scheme raised concerns it would struggle to meet current UK standards let alone tighter EU rules.

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Ian said: "You can see now they're proposing something which is not good enough."

Thames Water told the LDRS the scheme, which is still in the design stages, would meet UK water quality standards.

The pilot was commissioned at the start of September 2024 and run under two intensive testing, sampling and monitoring campaigns, known as sprints, along with a shorter targeted final sprint before it was decommissioned in December 2025.

A report on the results said iron concentrations in the treated wastewater in the first two sprints were "expected to have a significant detrimental impact on the receiving water body" i.e the River Thames.

It said the technology tested during these studies was not "suitable for full-scale implementation" as it could not reliably meet treated water quality standards for iron.

The technology was adjusted for a shorter final sprint and produced results closer to the scheme's targets for iron removal, which the report said could be improved further.

But the report also found the technology faced challenges in "achieving tighter treated water PFOS targets", known as a 'forever chemical'.

Ian said: "If you compare what they're achieving and what they've done compared to these European standards that we're going for in the petition, they are a country mile away from it."

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The Government must consider holding a debate in Parliament on the petition if it reaches 100,000 signatures by November 1.

A Thames Water spokesperson said: "The proposed Teddington direct river abstraction project would provide up to 75 million litres of water for London each day during drought.

"We'd replenish the river with recycled water, protecting river levels and the local environment.

"Water recycling is a tried and tested method used across the world.

"We'd like to reassure local communities that the project would meet water quality standards set by the Environment Agency and will comply with all relevant regulatory and legal requirements, which are set by UK Government.

"We will continue to engage in discussions on how to protect our waterways for the future."

Thames Water plans to apply to the Government for a development consent order to build the project in early 2027.