TFA in your tap water: let's do the maths

On 22 July 2026, the European Food Safety Authority (EFSA) cut the tolerable daily intake for TFA (trifluoroacetic acid) by 72%, the smallest forever chemical in the PFAS family. Research from the University of York has already found it in 31 of 32 UK rivers tested. Faced with that, a simple question: is current guidance actually protective enough? We did the maths, by body weight.

What TFA actually is

TFA (trifluoroacetic acid, CF3COOH) is an ultra-short-chain perfluorocarboxylic acid, the smallest molecule in the PFAS family under the OECD's definition. It doesn't bind to soil, stays highly mobile in the environment, and dissolves readily in water, which explains how widespread it's become.

Where it comes from

TFA has two main sources. One is the breakdown of several fluorinated pesticides approved in Europe, EFSA has identified active substances including flufenacet, tritosulfuron, flurtamone and saflufenacil as direct precursors. The other is the breakdown of fluorinated industrial gases used as refrigerants (HFCs, HCFCs) and aerosol propellants. The result: it turns up in soil, groundwater, crops, and in more unexpected places too, a PAN Europe study published in April 2025 measured an average concentration of 122 µg/L in recent-vintage European wines (2021 to 2024), against no detectable trace in wines bottled before 1988.

What UK research shows

Research from the University of York found TFA in 31 of 32 UK rivers sampled, underlining how widespread this pollutant already is in British water sources. Unlike most other PFAS, TFA isn't part of the Drinking Water Inspectorate's (DWI) monitoring framework: DWI guidance covers 48 individual PFAS with a combined guideline value of 0.1 µg/L, tightened in August 2024, but TFA itself sits outside that list.

The DWI has commissioned exploratory research into TFA levels specifically, but this hasn't yet turned into routine monitoring or a dedicated limit, in the UK or the EU.

What the EFSA decision changes

On 22 July 2026, EFSA lowered the tolerable daily intake (TDI) for TFA from 0.05 to 0.014 mg per kilogram of body weight per day, a 72% cut. The agency is still cautious on other points: it considers TFA unlikely to be genotoxic, but acknowledges a lack of long-term toxicity and carcinogenicity data, which led it to apply an extra uncertainty factor in its calculations. Recent animal studies have shown effects on reproduction and thyroid hormone levels, though the scale of the risk to humans hasn't been established.

Is there enough precaution built in?

The tolerable daily intake is expressed “per kilogram of body weight, per day”: it's a figure to multiply by your own weight, not a fixed number for everyone. For a reference adult of 70 kg (the standard weight used in toxicology), that gives: 0.014 x 70 = 0.98 mg of TFA a day, from all sources combined, water, food and wine included.

As a cautious simplification, if that whole allowance were assumed to come from water alone (around 2 litres a day), that works out to a theoretical ceiling of 490 µg/L (0.98 mg ÷ 2 L). There's no UK or EU limit specifically for TFA to compare that against yet, but it's a useful benchmark: our own testing found 0.9 µg/L in tap water, more than 500 times below that theoretical ceiling. Here's the same calculation across different body weights:

*Theoretical maximum concentration if drinking water (2L/day) were the only source of TFA, calculated from EFSA's tolerable daily intake.

Even for a 10kg child, the theoretical ceiling (70 µg/L) sits well above the 0.9 µg/L found in our own tap water testing. A young child typically drinks less than 2 litres a day, so this remains a cautious approximation rather than an exact measure of real-world exposure.

Does that mean there's nothing to worry about? Not entirely. EFSA itself applied an extra safety margin in its calculation, citing a lack of long-term toxicity data. The precautionary principle still justifies reducing exposure, even where it currently sits under any reasonable threshold. And regulation is likely to keep moving toward more caution, not less, over the coming months.

Why it's such a difficult pollutant to filter

Its small molecular size and high water solubility make TFA particularly hard to remove through conventional water treatment, unlike longer-chain PFAS. It's a genuine technical challenge for the whole water treatment sector, not just for Sküma Water.

What the MY™ Station from Sküma Water actually does

Across the sum of PFAS, the MY™ Station from Sküma Water removes more than 99% of the substances tracked under DWI guidance, a result certified by an independent COFRAC-accredited laboratory.

We went further and tested TFA specifically, something we're currently the only ones to have done and to be able to demonstrate with lab results, beyond the PFAS already monitored by the DWI. In our tests, tap water contained 0.9 µg/L of TFA. At the MY™ Station's outlet, that drops to below 0.35 µg/L, a reduction of up to 61%.

TFA remains under active scrutiny, and regulation is likely to evolve over the coming months. What can be said today, with the data available: even without a dedicated concentration limit to measure against, water filtered by the MY™ Station shows concentrations far below what our calculations suggest would be cause for concern, with a comfortable safety margin whichever way regulation moves next. And today, we're the only ones removing TFA to any significant degree, a molecule that's notoriously hard to filter.

Frequently asked questions

Is TFA currently regulated in UK drinking water?

Not with its own dedicated limit. TFA sits outside the DWI's list of 48 monitored PFAS and their 0.1 µg/L guideline value, though the DWI has commissioned exploratory research into it.

Does the MY™ Station remove TFA completely?

No, not completely, a 100% elimination of TFA doesn't exist yet anywhere. The MY™ Station reduces its concentration by up to 61%, though, which makes it the only system capable of a result like that today.

How widespread is TFA in UK water?

University of York research found it in 31 of 32 rivers tested across the UK.

Where else is TFA found besides water?

In soil, crops, and more surprisingly in wine: a 2025 study measured average concentrations of 122 µg/L in recent-vintage European wines.

Sources

EFSA, opinion on the revised tolerable daily intake for TFA, 22 July 2026

University of York, TFA testing across UK rivers

UK Drinking Water Inspectorate (DWI), PFAS guidance and monitoring requirements

PAN Europe, TFA in European wine study, April 2025

Independent COFRAC-accredited lab report, MY™ Station, Sküma Water

Note: as of publication, there is no dedicated concentration limit for TFA in UK or EU drinking water regulation. The calculations in this article are cautious theoretical estimates (water assumed as the sole source of exposure), not a measure of real-world exposure, which also depends on diet and other sources.