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Forever chemicals surge during Thames Water drought pilot

newsAug 27, 202619692

Thames Water pilots for a plan to pump treated sewage from Mogden back into the River Thames raised perfluorooctane sulfonate, a PFAS 'forever chemical' and suspected carcinogen, to 6.3 nanograms per litre in one test and 8.7 nanograms per litre in another, compared with the UK surface water limit of 0.65 nanograms per litre. The company proposes abstracting up to 75 million litres a day from the Thames at Teddington in drought and replacing it with treated effluent delivered by a new tunnel, a scheme the company values at at least £350 million and is seeking a development consent order for. Technical notes from the pilots show a rapid breakthrough of PFOS above the legal threshold in less than one month and state keeping within legal limits would be operationally challenging, requiring frequent regeneration, reactivation, and replacement of carbon filters and significant additional expense. The pilots also recorded very high iron concentrations, which the documents say would have a significant detrimental impact on the river. Thames Water has publicly said the recycling system would not harm the river or public, but the company files seen by the Guardian show the treated sewage input would make it very difficult for the river to meet current standards for forever chemicals and pesticides. Ian McNuff of the campaign group Solar said, "In essence, they can’t make it work properly."

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