Raw drinking water sources across England are increasingly contaminated with toxic forever chemicals, prompting urgent calls for governmental intervention.

New analysis reveals widespread pollution, leading the water sector to demand a ban on these substances and for polluters to bear the cleanup costs.

Areas served by Affinity Water and Anglian Water have been particularly affected, with experts warning that the problem is likely far larger than currently estimated.

There are over 10,000 per- and polyfluoroalkyl substances (PFAS), commonly called forever chemicals due to their persistence in the environment. Among them, PFOS and PFOA are now banned after being linked to cancers, thyroid disease, and reproductive issues. However, little is known about the toxic effects of thousands of other PFAS. These chemicals are widely used in consumer products, industrial processes, and firefighting foams, resulting in pollution in water, air, soil, wildlife, and even human blood.

In an unprecedented move, the industry body Water UK has said it “wants to see PFAS banned and the development of a national plan to remove it from the environment which should be paid for by manufacturers.”

It described PFAS pollution as a “huge global challenge” and said: “The UK’s tap water is rated as the safest in the world, and companies are already taking action to reduce PFAS levels further.”

The European Union is considering a comprehensive regulation of all PFAS, but the chemical industry is resisting, and the UK currently has no plans for similar measures.

Major sources of PFAS pollution include airports, military bases, chemical manufacturers, sewage treatment plants, fire stations, metalworking companies, paper mills, leather and textile manufacturers, energy facilities, and landfills. Contaminated sewage sludge spread on farmland is another potential source. A report for the Environment Agency suggests there may be as many as 10,000 contamination hotspots nationwide.

Data from water companies, the Environment Agency, and the Drinking Water Inspectorate (DWI), obtained by The Guardian and Watershed Investigations, shows that PFAS are contaminating untreated drinking water sources across England.

In 2023, 199 untreated water samples contained PFAS levels exceeding 100 nanograms per litre (ng/l), the maximum guideline for treated drinking water set by the DWI. Water companies treat or dilute contaminated water to ensure compliance before it reaches consumers.

Among these samples, 137 came from Anglian Water and 54 from Affinity Water. South East Water, Southern Water, Thames Water, and Wessex Water also reported samples above the threshold. Anglian Water conducted 220,000 tests, the most of any company, followed by Southern Water with 75,000.

Anglian Water serves areas including Bedfordshire, Buckinghamshire, Cambridgeshire, Essex, Lincolnshire, Norfolk, and Suffolk.

The DWI has flagged that without the preventive action taken by Anglian Water, “there is or has been a significant risk of supplying water from” its works at Ulceby, Parsonage Street in Halstead, Barrow and Warren Hill, adding that without such action, the water “could constitute a potential danger to human health or could be unwholesome”.

High PFAS concentrations were detected near industrial zones, including Ulceby and Barrow in Lincolnshire, close to oil refineries and Humberside Airport. Ulceby samples contained 1,270ng/l of 6:2 FTS, a firefighting foam chemical, while banned PFOS and PFOA exceeded safety thresholds.

In Beck Row, near RAF Mildenhall in Suffolk, raw water contained 1,670ng/l of PFOS. Another source near RAF Marham in Norfolk reached 211ng/l. The bases may not be directly responsible, but their presence raises concerns.

A Ministry of Defence spokesperson said:“Ensuring the safety of our staff, personnel and the public is our number one priority and that’s why we are complying with the relevant legislation and regulations. As understanding of these chemicals has changed, we have responded accordingly. We have prioritised a programme of investigation of our sites, which has been agreed with the Environment Agency.”

In 2022, Watershed and The Guardian exposed that Duxford Airfield, a former RAF site in Cambridge, likely contaminated South Cambridgeshire’s drinking water. Now managed by the Imperial War Museum, the site is under investigation by the Environment Agency.

Affinity Water, which supplies parts of Bedfordshire, Berkshire, Buckinghamshire, Essex, Hertfordshire, Surrey, and several London boroughs, has reported high PFOS levels in Letchworth, Baldock, and Wheathampstead. One source in Denham was taken offline entirely due to contamination. The company has received regulatory notices related to five treatment facilities.

Other water suppliers, including United Utilities, South West Water, Severn Trent Water, Wessex Water, and South Staffordshire Water, have also received DWI notices.

Compared to other nations, the UK’s safety thresholds for PFAS in drinking water are significantly higher. The US has proposed a strict limit of 4ng/l, whereas the UK currently allows up to 100ng/l.

“Drinking water is a major source of exposure to PFAS,” said Dr Shubhi Sharma from the charity Chem Trust. “We must have stringent safety standards for PFAS in drinking water to protect people’s health, but the standards currently in place in the UK are outdated and not protective enough.”

Stephanie Metzger, a policy adviser at the Royal Society of Chemistry, said the industry has been asked to monitor for a limit of 100ng/l for 48 types of PFAS but said: “We shouldn’t stop there. No one chooses the water that comes out of their tap, so we want to see statutory PFAS limits for UK drinking water that are clearly and transparently defined and legally enforceable. We need to translate this new guidance into legislation that gives the regulator Ofwat defined criteria – and the power – to hold water companies to account.”

The forensic environmental scientist Dr Dave Megson, from Manchester Metropolitan University, says he “fears we are currently drastically underestimating the size of the problem” because the Environment Agency is not looking for enough types of PFAS.

“Current PFAS monitoring efforts are predominantly geared towards targeted assessments which involve looking for a specific number of PFAS – for drinking water it’s 47 compounds from 10 classes. Alternative testing methods that use a non-targeted approach are showing that this targeted approach only tells a fraction of the story,” said Megson.

“We recently calculated that only approximately 18% of PFAS contamination at a site in Lancashire would have been detected by relying on targeted methods alone.”

The Environment Agency states it is conducting catchment investigations, including at Barrow and Beck Row. It collaborates with the UK Health Security Agency, Food Standards Agency, and DWI. The government asserts that it is assessing PFAS contamination levels, sources, and associated risks to shape future policies and regulations.