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The drinking water watchdog for England and Wales has ordered companies to act after “forever chemicals” linked to cancer and other conditions were found in untreated water sources at levels it said “could constitute a potential danger to human health”.
Per- and polyfluoroalkyl substances (Pfas) are a group of manmade chemicals used for their waterproof and grease-resistant properties. These forever chemicals persist in the environment, can build up in the body and some have been linked to cancer, hormone disruption and fertility problems. Two of the most notorious, PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid) are now banned after being classified as carcinogens by the World Health Organization.
An analysis of Drinking Water Inspectorate (DWI) data by Watershed Investigations and partners found that the regulator had flagged Pfas issues in untreated water at hundreds of water treatment works, reservoirs, boreholes and supply systems serving more than 6 million people. The true number of people potentially affected will be much higher, as population data was not available for all the affected sites.
The analysis reported that water companies who have been ordered to improve their assets because of Pfas contamination include Anglian Water, where untreated supplies serving 4.2 million people are affected, and Wessex Water, serving 1.2 million.
Severn Trent Water, South Staffordshire Water and South West Water, who serve hundreds of thousands of customers, have also been told to act. Affinity Water has five waterworks at risk and United Utilities has two, but the number of people whose supplies may be affected by these could not be determined.
Some DWI notices cite “inadequate treatment process to remove Pfas”, while others warn of “increasing Pfas levels” that could breach the DWI’s safety limits. The regulator has given the companies deadlines to reduce the risk, typically by stepping up Pfas monitoring, improving treatment processes, or blending contaminated supplies with cleaner water from other sources to lower concentrations.
Major Pfas pollution sources include airports, military sites, chemical manufacturers, sewage treatment plants, fire stations, metal and paper mills, leather and textile factories, energy facilities, and waste sites such as landfills. Pfas-laden sewage sludge spread on farmland can also taint soil and water, and Pfas are used in pesticides as both an active agent and a spreading agent. An Environment Agency report estimated up to 10,000 potential hotspots nationwide.
Affinity Water, which supplies parts of Bedfordshire, Berkshire, Buckinghamshire, Essex, Hertfordshire, Surrey and several London boroughs, has been served notices relating to the banned carcinogens PFOS and PFOA.
Affinity’s sites in Holywell, Baldock and Wheathampstead in Hertfordshire, and Ardleigh in Essex, have been flagged for PFOS, while water at the Blackford works in Hillingdon is at risk from PFOA. The water company has until 2029 to either blend the contaminated supplies with cleaner water or install better filtration at their works.
Pfas has been found to be a risk in South Staffordshire Water’s supplies in Cambridgeshire, with contamination from fire-fighting foams at Duxford airfield thought to be one likely source. Severn Trent Water’s Cropston works are at risk from rising Pfas levels, while all of South West Water’s affected supplies are located in the Isles of Scilly, and United Utilities has has Pfas notices served against two of its works – one for Royal Oak in Southport and the other for Wickenhall.
Since 2007, the UK’s Pfas limits in drinking water have dropped dramatically. Initially set at 10,000 nanograms/l for PFOA and 1,000 ng/l for PFOS, the PFOA limit fell to 5,000 ng/l in 2009, and by 2021 both were reduced to 100 ng/l amid emerging toxicity evidence. In January, pressure from experts led the DWI to cap the total of 48 Pfas types at 100 ng/l.
Prof Hans Peter Arp, a Pfas expert, said the UK’s contamination problem was “large but by no means unique,” noting that “Pfas has seeped into drinking water supply zones around the world for over 50 years”. He explained that drinking water limits were only introduced about 25 years ago, initially covering just a few compounds like PFOA and PFOS, and are “not protective enough”.
Arp contrasted the UK’s former limit of 10,000 ng/l for PFOA in 2007 with Denmark’s much stricter current standard of 2 ng/l for a group of four Pfas, calling it “a decrease by more than 5,000”. He warned that “there is likely a portion of the population that has been affected” and said tackling Pfas will require upgrading treatment technology, including “nanofiltration or ion exchange resins”, as well as preventing future emissions and cleaning up contaminated soil and groundwater.
The cost of cleaning up Pfas has been estimated at £1.6tn across the UK and Europe over a 20-year period, an annual bill of £84bn.
A Water UK spokesperson said Pfas pollution was “a huge global challenge” and called for the chemicals to be banned and for “a national plan to remove it from the environment – which should be paid for by manufacturers”.
They added: “All water companies have to meet stringent government standards and testing, including on Pfas, so we can all have complete confidence in the quality of our tap water whenever and wherever we use it.”
The EU is considering a wide-ranging restriction across thousands of Pfas but industry is pushing back hard and the UK does not have plans to follow suit.
A government spokesperson said UK drinking water was “of an exceptionally high standard and among the best in the world”. They added: “Water companies must conduct rigorous tests and sampling, and there is no evidence that water from consumer taps exceeds the safe levels of Pfas, as set by the DWI in 2021.”
They said £2bn in private-sector investment had been committed “to further improving drinking water quality, including tackling Pfas and replacing the remaining lead pipes in the network”.
Dr Shubhi Sharma of Chem Trust said: “Drinking water is a major source of Pfas exposure. The current UK standards for Pfas in drinking water are not protective enough. The UK government needs to match the EU and bring in stringent thresholds.”
She added that removing Pfas from supplies was “astronomically expensive” and urged ministers to apply the polluter-pays principle “so that chemical companies are paying these costs and not the public through their water … what we really need is to turn off the Pfas pollution tap at the source by urgently stopping the production and use of these forever toxic chemicals. Just focusing on cleaning up Pfas pollution is only a very expensive sticking plaster”.
