Are there PFAS "forever chemicals" in UK tap water?

Part of our tap water guide

"Forever chemicals" is a dramatic name for a family of at least 5,000 substances. Here is what the DWI found in 2025, why your own tap may differ, and what a 20-in-1 strip can and cannot check.

By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026

Are there PFAS in UK tap water?

Yes, mostly at low levels and at some works, according to the Drinking Water Inspectorate. It describes PFAS (per- and polyfluoroalkyl substances) as a family of at least 5,000 substances, called "forever chemicals" because they persist in the environment. The DWI says the low levels detected in some untreated water used for public supplies have no acute or immediate impact on human health, and that drinking water is a small proportion of the possible overall exposure.

In 2025, water companies across England and Wales ran more than 666,000 analyses for individual PFAS, says the DWI's Drinking Water 2025 report. It sorts results into 3 tiers, and the table shows its 2025 sum-of-PFAS calculations (the sum of 48 named PFAS) for England.

The DWI says sampling is aimed at higher-risk sites, so this is not a simple measure of average national exposure. Of 989 treatment works in supply in England in 2025, tier 2 concentrations were found in treated water at 82 (8.29%). The DWI says tier 2 stays below its health-based guidance value of 0.1 µg/L for the sum of PFAS.

Two treated-water samples were reported in tier 3, both PFOS from one small Southern Water works near a disused airfield. The DWI also reported 2 sum-of-PFAS events and judged the water supplied in each potentially unwholesome.

• Wessex Water, Charlton Minety works. 0.103 µg/L in February 2025 and 0.098 in March, supplying about 6,700 consumers after further blending.
• Hanningfield works. 0.106 µg/L on 6 October 2025, after raw water operation changed. Later samples fell to tier 2.

The DWI says exceeding a guideline does not mean health has been harmed.

Is there a legal limit for PFAS in UK tap water?

Not in England or Wales. The DWI says there are no statutory standards for PFAS in drinking water there, and no World Health Organization guideline value either. It has set tiered guideline values instead. These include 0.1 µg/L (0.1 parts per billion) for the sum of 48 named PFAS, in guidance updated in March 2025, and water companies are required to comply with them.

Which water companies have PFAS at their sources?

All 12 rows in the DWI's 2025 table have at least one abstraction point with tier 2 detections, from 0.22% of points to 7.69%. These are sources, not taps.

The DWI calls Anglian Water the most notable company in the data. It has five notices and one undertaking in place requiring PFAS mitigation, generally due for completion around 2031.

Why might PFAS at my tap differ from the figure for my area?

The area figure is a summary, not a reading from your tap. The DWI's reports give several reasons the two can differ.

• Targeted sampling. Monitoring concentrates on the sources and works most likely to be affected, so results must be read in that context.
• Blending. Water from a works can be blended within the network before it reaches a tap.
• Private supplies. Company figures do not cover them. The DWI's guidance for councils lists possible catchment sources such as fire stations, military bases and landfill sites, and adds that PFAS have been found where no such link is apparent.

“If you're on a private supply, or you simply want to know what's coming out of your own tap, I would check it yourself rather than lean on an area summary. Those figures describe sources and works, and what reaches your kitchen can look different.”

Defra's PFAS Plan says PFAS have been found in about 80% of surface water samples and about 50% of groundwater samples. A strip cannot show PFAS, but it can repeat readings on its other pads at different taps and times. Our water testing guide shows how.

Can forever chemicals be filtered out of water?

At treatment works, yes, to varying degrees. The DWI's bench-scale and pilot-scale studies tested water treatment processes, and its executive summary reports the following.

• The best nanofiltration and reverse osmosis membranes removed 99% of many PFAS, and over 80% of short-chain PFAS.
• Activated carbon preferentially removed larger PFAS, and four-carbon PFAS passed through almost immediately.

Our reverse osmosis guide and filter jug guide cover home filters.

How can you test for PFAS, at home or in a well?

Only in a laboratory. The DWI says PFAS are in jackets, personal care products and sampling equipment, so the work needs PFAS-free equipment, and only a few labs can do it to the quality required. The United Kingdom Accreditation Service (UKAS) accredits laboratories and lists those approved for PFAS analysis.

For private supplies in England and Wales, the DWI says councils prioritise high-risk supplies for sampling when analysis is available. Owners whose supply shows an individual PFAS above 0.1 µg/L are advised to contact their council's environmental health team.

What can a strip show at my tap, and what is the next step?

It cannot show PFAS, because no pad reads them, and we do not claim the test for PFAS. For PFAS, the next step is an accredited laboratory, or your council's environmental health team if you have a private supply. The WaterKit Water Test Kit has a 20-in-1 strip. Fill a clean glass, dip a strip, wait 30 to 60 seconds and match the pads to the chart, or enter the colours in our free results checker. It indicates chlorine, hardness, pH, nitrate and copper at your tap.

• The strip cannot read lead at the UK limit, so see our lead pipes guide.
• The mercury, chromium, aluminium, iron, nitrite and fluoride pads only change colour above their UK limits, so a clear result on those pads is not a pass.
• The optional bacteria test is a presence screen for coliforms, read after 24 to 48 hours. A strip result has no legal effect.

The area figure is an average picture built from sampling aimed at higher-risk sites, and the DWI's examples show blending and raw water changes can make a tap differ. Repeating the chlorine, hardness, pH, nitrate and copper pads at different taps and times would indicate whether your own supply changes between them, which is the reason to test. Best pack: 20 strips, enough to check your tap at different taps and times on the pads the strip does read, £5.99 (or £10.99 with a bacteria test), with free 2nd Class delivery on every order. See the kit

Your PFAS questions

Does bottled water contain PFAS? Are there forever chemicals in bottled water?

The DWI pages and Defra's PFAS Plan that we read give no PFAS figure for bottled water, so we cannot say either way.

Can forever chemicals be filtered out of water?

The DWI's studies found some treatment processes remove most PFAS, but the sources we read give no home filter figure.

How to test for forever chemicals in water?

In a UKAS-accredited laboratory, as far as the DWI pages we read show.

How to test for PFAS in well water?

In an accredited laboratory too. See our well and borehole water guide.

Sources

1. Drinking Water Inspectorate, PFAS and Forever Chemicals (undated page; what PFAS are, no statutory standard, no WHO value, 0.1 µg/L for the sum of 48 PFAS, effect of exceeding it, private supplies, laboratory capacity; read 29 October 2026).
2. Drinking Water Inspectorate, Perfluoroalkyl and polyfluoroalkyl substances (PFAS), in Drinking Water 2025, summary of the Chief Inspector's report for England (undated page; Tables 13 and 16, 989 works, 82 tier 2 locations, the Southern Water, Wessex Water and Hanningfield events; read 29 October 2026).
3. Drinking Water Inspectorate, Poly and Perfluorinated Alkyl Substances (PFAS) (private supplies guidance, undated; catchment sources, council role, UKAS; read 29 October 2026).
4. Drinking Water Inspectorate, Bench-Scale and Pilot-Scale Water Treatment Efficacy Studies of PFAS Removal (DWI 70/2/350, published 29 April 2025; read 29 October 2026).
5. Drinking Water Inspectorate, Bench-scale executive summary (undated PDF; membrane, carbon, ion exchange and oxidation results; read 29 October 2026).
6. Defra, PFAS Plan: building a safer future together (© Crown copyright 2026, undated in the text we read; PFAS found in about 80% of surface water and 50% of groundwater samples; read 29 October 2026). We read only the part of the Plan before its drinking water and bottled water sections, so the bottled water answer above covers only the part we read.

Contains public sector information licensed under the Open Government Licence v3.0.