This PFAS is in almost every UK river – here’s how monitoring must change

In a comprehensive new study, researchers from the University of York have found trifluoroacetic acid (TFA), a highly persistent and mobile PFAS compound, in 31 of 32 rivers sampled across the UK.

The investigation, funded by environmental charity Fidra, marks the first national-scale survey of TFA in UK surface waters.

It confirms what many in the sector have suspected: TFA is widespread, under-regulated, and slipping through the cracks of current water monitoring frameworks.

Only on the radar of environmental monitoring professionals the last few years, TFA is an incredibly interesting pollutant in itself and a useful index for other pollutants, too.

For professionals involved in water quality monitoring, wastewater compliance, and catchment assessment, these findings signal an urgent need to rethink how (and whether) current systems can detect and respond to this new generation of so-called “forever chemicals.”

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Widespread, persistent and virtually unregulated

TFA is an ultrashort-chain perfluoroalkyl substance (PFAS) formed through the degradation of other synthetic chemicals, including PFAS-containing pesticides, fluorinated refrigerants, and pharmaceuticals.  

Unlike longer-chain PFAS (e.g., PFOS or PFOA), TFA is extremely water-soluble and does not degrade under environmental conditions.  

It is not removed by conventional water treatment processes and can travel unimpeded through water systems.

• Despite its mobility and persistence, TFA is currently unregulated in UK water or environmental law:
• There is no requirement for water companies or regulators to monitor TFA at drinking water abstraction points or in treated effluent discharges.
• There are no statutory limits or standards for TFA in UK drinking water.
• TFA is not included in any UK environmental quality standards (EQSs) for rivers or groundwater.
• Wastewater regulation does not include PFAS parameters, including TFA, even though wastewater treatment works are a known and active pathway for PFAS release to the environment.

This means that at present, TFA can enter and exit the water system virtually undetected and unmanaged, regardless of concentration.

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What is the scale of the problem?

The University of York’s study, conducted year-round across 54 locations in 32 rivers throughout England, Wales, Scotland, and Northern Ireland, revealed:

• TFA contamination at 98% of sampling sites.
• A UK-wide average concentration of 2,211 ng/L.
• The second-highest river TFA concentration ever recorded globally (78,464 ng/L, in the River Kelvin, Glasgow).
• No strong link between land use and contamination levels, suggesting a complex mix of urban, atmospheric, and possibly industrial or agricultural sources.

Given TFA’s environmental behaviour, its presence in surface water almost certainly implies its presence in groundwater and drinking water, especially in areas where surface water is used as a supply source.

How our monitoring systems can adapt

1. Current monitoring systems are not detecting TFA

TFA is not part of the UK’s drinking water compliance framework. While the Drinking Water Inspectorate (DWI) offers voluntary guidance levels for 47 PFAS (0.1 µg/L for individual substances, 0.5 µg/L total), TFA is not among them.  

Nor is it part of the mandatory statutory standards for water quality.

The DWI recently announced that it has commissioned research into TFA levels in drinking water, but this is exploratory and has not yet translated into routine monitoring requirements.

In wastewater, the Environment Agency does not require effluent monitoring for PFAS or TFA, and there are no discharge limits or permitting conditions in place for these substances under the Environmental Permitting Regulations.  

The Urban Waste Water Treatment Regulations (UWWTR) also do not include PFAS.

This regulatory gap means water and wastewater operators are not legally required to know whether or not they are releasing or distributing TFA, even at concentrations in the tens of micrograms per litre.

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2. TFA highlights a new class of chemical risk

Unlike the better-known, longer-chain PFAS compounds, TFA belongs to a group of ultrashort-chain, highly mobile, non-adsorbing substances.  

These chemicals move through the environment in ways traditional contaminants do not.  

They resist activated carbon treatment, are unaffected by biological filtration, and often evade conventional analytical techniques.

For water monitoring professionals, this requires:

• Updated analytical methods tailored to TFA and similar substances.
• New sampling protocols that capture ultrashort-chain PFAS behaviour.
• Better understanding of diffuse input pathways, such as atmospheric deposition, urban runoff, or degradation of legacy chemicals.

3. Effluent may be a key pathway

Some of the highest TFA levels found in the study were in rivers downstream of urban centres, suggesting that treated municipal wastewater may be a significant contributor to environmental TFA loads.

Yet there is currently no obligation for utilities or industry to test for TFA in effluent, or even know whether TFA is forming as a by-product during treatment.

For the wastewater sector, this points to the need for:

• Catchment-specific risk assessments of PFAS contributions,
• Inclusion of TFA in emerging contaminant monitoring programs,
• Dialogue between regulators and operators to define future permitting thresholds.

An opportunity to get ahead of regulation

Across Europe, regulators are already moving.  

The German Federal Environment Agency has formally proposed that TFA be classified as toxic for reproduction under EU chemicals legislation.  

If approved, this could lead to product restrictions and eventually drive effluent standards at the EU level.

In the UK, the policy landscape is less developed. But momentum is building:

• NGOs such as Fidra and CHEM Trust are campaigning for group-based restrictions on PFAS.
• The DWI is increasing its focus on emerging contaminants.
• Public concern around “forever chemicals” is rising.

For water monitoring professionals, this is a critical time to develop the data, methods, and institutional knowledge required to respond quickly if TFA, or other ultrashort-chain PFAS, are brought under regulatory control.

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The widespread detection of TFA in UK rivers, and the absence of any regulatory oversight, presents a serious blind spot in how the UK monitors and manages chemical pollutants in water.  

While not acutely toxic at current levels, TFA’s extreme persistence, mobility, and potential for long-term harm demand proactive attention.

Water monitoring professionals will play a central role in shaping the UK’s response, through fieldwork, lab analysis, data interpretation, and engagement with regulators.  

As the PFAS challenge evolves, understanding and tracking TFA may be the key to staying ahead of a shifting chemical landscape.