Key facts
- Pilot tests for Thames Water's water recycling scheme showed 'forever chemical' levels up to 13 times the legal limit.
- The scheme involves pumping treated sewage into the River Thames during drought conditions.
- High levels of iron were also found in the treated water, posing a risk to the riverine environment.
- Thames Water claims the pilot data does not reflect the final operational system and that an environmental permit is necessary.
- The project faces opposition from environmental groups and local representatives due to potential ecological harm.
Levels of toxic 'forever chemicals' surged to 13 times the legal limit during pilot tests for Thames Water's controversial water recycling scheme, which aims to pump treated sewage into the River Thames during droughts. Data from the company's internal technical notes, seen by The Guardian, revealed that perfluorooctane sulfonate (Pfos), a suspected carcinogen, rapidly exceeded thresholds in less than a month of operation.
Thames Water's recycling system is designed to abstract up to 75 million litres of water daily from the Thames at Teddington and replace it with treated sewage from the Mogden plant. This initiative is intended to bolster water supplies amid rising populations and climate change-induced droughts. However, the pilot results indicate that the input of treated sewage would make it difficult for the water to meet current standards for forever chemicals and pesticides.
Despite public assurances that the scheme, with an estimated cost exceeding £500 million, would not harm the riverine environment or public health, the technical documents highlight significant challenges. The company noted that maintaining legal limits would be 'operationally challenging' and require substantial additional expense for filter maintenance. High levels of iron were also detected, which the document states would have a 'significant detrimental impact' on the river.
Campaign groups like Solar, along with local councils and MPs, oppose the project, citing concerns about irreversible environmental damage. They argue that the pilot failures demonstrate the unreliability of the proposed system. The Environment Agency, which previously rejected a similar scheme in 2019, stated that rigorous environmental assessments are required before any development can begin, emphasizing that environmental protection and sustainable development must align.
A Thames Water spokesperson acknowledged the operational challenges but stated the pilot was designed to test technologies for the final design. They added that the project would not operate without an environmental permit and expressed a desire for a ban on Pfas, with manufacturers, not bill payers, funding its removal from the environment.