We asked the regulator for PFAS results by area

Everywhere else on this site we say the same thing: nobody can tell you how much PFAS is in the water at your postcode, because the results are not published by location. That is a strong claim, so this page is the evidence behind it.

In July 2026 we asked the Drinking Water Inspectorate for the underlying data. The request was refused. Below is what we asked for, what the Inspectorate said, and what is actually known in the absence of the data.

What we asked for

On 23 July 2026 we made a request under the Environmental Information Regulations 2004 for the PFAS monitoring results reported to the Inspectorate by water companies in England and Wales, covering the most recent twelve months of complete data, at the lowest geographic level held. For each result we asked for:

• the water company
• the supply zone or site identifier, and its name
• the sample date
• the determinand, meaning the individual PFAS compound and the sum-of-48 figure where it is calculated
• the measured value and its unit
• the limit of detection or reporting limit, so that a genuine non-detection could be told apart from a sample that was never tested

That last point matters more than it looks. Without a detection limit, a blank result and a clean result are indistinguishable, and any map built on the data would quietly present untested areas as safe ones.

What the Inspectorate said

The request was refused on 5 August 2026 under regulation 12(4)(b) of the Environmental Information Regulations, which allows a public authority to refuse a request it considers manifestly unreasonable. The refusal was made on cost grounds, and the Inspectorate carried out the public interest test that the regulations require, concluding in favour of withholding. The reference is EIR2026/16348.

The reasons given were that answering would require several members of staff to extract and quality check the data from a very large dataset, that there are, in the Inspectorate's words, millions of parameters reported, that this volume could not be handled in Microsoft Excel so additional tooling would have to be developed, and that the work would take several days.

The Inspectorate also offered advice on narrowing the request, suggesting asking for a single tier of results, and pointed to the summary figures published in its annual report. It added that a narrowed request would still be likely to be refused in part under other exceptions, giving national security as an example.

What this does and does not mean

It does not mean PFAS goes untested. Water companies in England and Wales are required to monitor it and to report what they find. It does not mean the Inspectorate acted improperly either: the regulations permit exactly this refusal, and the letter sets out the reasoning and the appeal route.

What it means is narrower and more stubborn. The results exist, the regulator holds them, and they are not available to the public at the level of a supply zone. So when a website offers to tell you the PFAS level in your postcode, it is not working from the monitoring data, because that data has not been released.

What is known: the tier system

There is no statutory PFAS standard for drinking water in England and Wales. What exists instead is regulator guidance, published by the Inspectorate in March 2025, setting a three-tier system that applies both to individual PFAS compounds and to the combined sum-of figure:

For scale, the Inspectorate notes that 0.1 µg/L corresponds to a daily intake of 0.0033 µg per kg of body weight for a 60 kg adult drinking two litres a day.

What we do instead

We do not estimate. Our PFAS tracker says what is known and says plainly where nothing is known, rather than filling the gap with modelled numbers that would look like measurements. If you want the background on what PFAS are and where they come from, start with our guide to PFAS in UK water. If you would rather reduce your exposure regardless of what the data eventually shows, reverse osmosis is the treatment with the strongest evidence against PFAS, covered in our PFAS filter guide.

Sources

• Drinking Water Inspectorate, response to information request EIR2026/16348, 5 August 2026. Held by us; quoted above and verifiable from the Inspectorate by reference number.
• Drinking Water Inspectorate annual report, which publishes summary PFAS figures including sample counts per tier.
• Drinking Water Inspectorate, guidance specific to PFAS in drinking water, version 1.1, March 2025, for the tier thresholds and the actions required at each tier.

Last updated 5 August 2026. If the Inspectorate releases the underlying results, we will publish them here and say so on this page.