Thames Water pilots show PFAS levels soaring far above legal limits
Pilot trials for Thames Water’s drought-relief recycling scheme released PFAS concentrations up to 13 times the legal threshold, contradicting the company’s assurances that the project would not harm the River Thames.
During trial operations of Thames Water’s proposed water-recycling project, concentrations of the persistent chemical perfluorooctane sulfonate rose to 6.3 and 8.7 nanograms per litre, exceeding the UK surface-water limit of 0.65 nanograms per litre by as much as 13 times. The pilots also recorded high iron levels that could adversely affect the River Thames. While the utility has publicly claimed the scheme will not endanger the river or public health, the internal technical notes acknowledge that staying within legal limits would require frequent carbon-filter replacement and significant extra expense.
The company seeks a development consent order for a £350 million project that would pump treated sewage into the Thames during droughts, but the findings have prompted criticism from the campaign group Solar and Liberal Democrat MP Munira Wilson. The Environment Agency, which previously rejected a similar plan in 2019, is reviewing the data as the project moves toward a permit application. Cost estimates have already risen from £350 million to over £500 million amid the utility’s £20 billion debt burden.
Why it matters
The trial shows a major water-reuse plan could worsen river pollution, raising environmental and public-health concerns.
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