“Forever chemicals” with potential toxicity, known as per- and polyfluoroalkyl substances (PFAS), have been discovered in the drinking water sources of 17 out of 18 water companies in England.

The Drinking Water Inspectorate (DWI) reported that 11,853 samples from both raw and treated water tested positive for PFAS, a group of over 10,000 human-made chemicals used in various industrial processes, consumer products, and firefighting foams.

The detection of PFAS has raised concerns, with some substances, such as PFOS and PFOA, previously linked to cancers, immune system issues, fertility problems, thyroid disease, and developmental defects in unborn children.

The DWI says the “dangers of PFAS have become a growing concern due to their persistence in the environment, ability to accumulate in the human body, and potential health effects”.

Despite most PFOS and PFOA being banned, the DWI found high concentrations in raw untreated water. PFOS was discovered at 18 times the limit considered high risk, while PFOA was found at 1.5 times the limit.

The DWI categorises PFOS and PFOA contamination risk into three tiers, with tier 3 being high risk, prompting the need for action to dilute PFAS or remove the water source from public supplies.

While there are no set limits for the majority of the 10,000 PFAS substances, the DWI identified 47 PFAS for water companies to monitor. Of these, 35 were detected, and an additional PFAS compound was found.

Affinity Water and Anglian Water faced significant PFAS issues, with several raw water samples exceeding DWI limits. However, the DWI asserted that blending contaminated water with another source prevents high concentrations from reaching taps.

“The report shows that there are people who are drinking medium-risk water,” said Stephanie Metzger, a policy adviser at the Royal Society of Chemistry (RSC).

Eight out of twelve water companies providing PFAS data in treated water had 398 samples with PFAS above 10ng/l, categorised as medium risk.

“We don’t think anyone should be drinking medium-risk water … the toxicology data shows the risk of health effects becoming more over time as PFAS builds up in our body,” said Metzger.

The Royal Society of Chemistry (RSC) is advocating for stricter regulations, urging a tenfold reduction of the limit for individual PFAS types from 100ng/l to 10ng/l. This proposal aligns with the EU and Scotland’s stricter limit of 100 ng/l for the sum of 20 specific PFAS in treated water.

The RSC aims to bring England and Wales in line with these stricter standards and suggests the establishment of a chemicals agency for PFAS and other contaminants.

Dr David Megson, a forensic environmental scientist from Manchester Metropolitan University, said: “Our guideline values for PFAS in drinking water are not as stringent as other countries, yet it is still a challenge for water companies to provide water with PFAS levels below these limits.

“Ultimately it is water companies and consumers who are picking up the bill to try to manage these contaminated supplies, not the polluters. Urgent action and investment is required.”

The RSC also calls for more frequent monitoring and emphasises the need for information disclosure, as some companies remain uncertain about the use of PFAS in their products and processes.

“There are so many PFAS out there and we are only testing for 47 and there are so many information gaps. There could be more PFAS out there we are exposed to. There needs to be more broad testing,” said Metzger.

“We really think companies need to do a PFAS audit so they can know what PFAS is in their supply chain and factories,” Metzger added. “How can water companies do a risk assessment [of their area] if companies don’t even know they’re using it?”

Dr Clare Cavers from the environmental charity Fidra, described the findings as “extremely alarming, in particular as the acceptable limit set by the DWI for the banned toxic forever chemical PFOS is much higher than in other parts of the world”.

She added:“With a recent study finding that PFOS can pass to children in the womb, [it] is gravely concerning.”

Anglian Water said it had “robust monitoring and reporting systems in place” and that it tested for PFAS compounds “at all of our water treatment works on a risk-based frequency as per regulatory requirement and between”.

It added that it was “proposing more than £68m of investment to upgrade our treatment processes to reduce PFAS at 15 sites across our region” between 2025 and 2030.

Southern Water said it had been “monitoring levels of key forever chemicals in water sources, even before new guidance requiring us to do so was issued. No results have been found in our sources of drinking water exceeding the maximum permitted of 100ng/l of PFAS.” It said it was investing £3bn between 2020 and 2025 on its network.

Cavers said: “The levels of PFOS detected in these samples from England water companies are especially worrying because PFOS restrictions have been in place for over a decade, and meanwhile other forever chemicals with similar or greater toxicity continue to be used widely, and to accumulate around us.

“The persistence, bio-accumulation and toxic properties of PFAS, with some lasting thousands of years in the environment, mean the pollution we cause today will last for generations to come.”

In a statement received after publication, an Affinity Water spokesperson said: “We want to reassure customers that we have processes in place to monitor sources of water in the environment closely for PFAS concentrations and remove or blend sources, where necessary, to ensure there are no typical concentrations of PFAS in the drinking water that is supplied to customers.”

A Water UK spokesperson said companies “adhere to high standards set by regulators, with virtually all samples meeting their strict tests”.

Despite these alarming findings, the Department for Environment Food and Rural Affairs, the Environment Agency, and the DWI declined to provide comments on the issue.

The discovery of PFAS in England’s drinking water highlights the urgent need for comprehensive regulation, monitoring, and public awareness to address potential health risks associated with these persistent chemicals.