Bottled Water Across 11 Countries Passes PFAS Limits, but One Unregulated Acid Slips Through

Bottled water has long been marketed as a pristine alternative to the tap, a product whose value rests on the promise of purity. A new international study now puts that promise to one of its most demanding tests yet. Writing in the journal Environmental Chemistry Letters, a team led by Grégorio Crini of the Université Marie et Louis Pasteur in Besançon and Dario Lacalamita of the University of Bari reports the results of a sweeping meta-analysis of per- and polyfluoroalkyl substances, the notorious class of synthetic chemicals often called forever chemicals, in bottled water sold across eleven countries on three continents. The headline finding is reassuring on one front and troubling on another: none of the twenty PFAS compounds regulated under the European Drinking Water Directive was detected above the limit of quantification in any sample, yet a single unregulated ultrashort-chain compound, trifluoroacetic acid, turned up systematically in waters from several countries, sometimes at concentrations far above everything else the researchers measured.

The scale of the analysis is what sets it apart. The team compiled data for 65 different PFAS compounds, including all twenty substances covered by the European regulatory list, across 163 bottled water samples drawn from 34 brands purchased in France, Italy, Belgium, Romania, Portugal, Lithuania, Georgia, Morocco, the United States, Mexico, and China. That geographic breadth matters because bottled water is a global commodity, and most existing studies of PFAS in drinking water have focused on municipal tap supplies within single countries or regions. Data on bottled water specifically have remained surprisingly sparse, even though millions of consumers treat it as their primary source of drinking water and even though natural mineral waters are subject to a different, and in some respects less chemically prescriptive, European regulatory regime than tap water.

PFAS are a family of thousands of synthetic chemicals built around chains of carbon atoms bonded to fluorine, one of the strongest bonds in organic chemistry. That carbon-fluorine backbone is what makes them so useful in products ranging from nonstick cookware and water-repellent textiles to firefighting foams, and it is also what makes them extraordinarily persistent in the environment. Some members of the family are linked to cancer, liver damage, immune suppression, and endocrine disruption, and they accumulate in the human body over years of exposure. Drinking water is considered a major route of human exposure, which is why the European Union’s Drinking Water Directive, adopted in 2020, set a cumulative limit of 100 nanograms per liter for the sum of twenty specific PFAS compounds. The new study checked every sample against that benchmark and found that the sum of the twenty regulated compounds stayed below 56 nanograms per liter in all cases, comfortably within the legal limit.

That compliance result is genuinely good news for the bottled water industry and for consumers who rely on it. It suggests that the sources feeding commercial bottling operations, which are typically deep aquifers or protected springs rather than surface waters, have so far largely escaped the contamination that has plagued many municipal supplies downstream of industrial dischargers and firefighting training sites. It also suggests that the treatment and bottling processes themselves are not introducing the longer-chain, regulated PFAS in measurable amounts. For the twenty compounds that regulators in Europe have prioritized, the message of this study is that bottled water, at least the 34 brands examined here, is currently a minor exposure pathway.

But the study’s second message is where the scientific and regulatory interest really lies. Among all 65 compounds screened, the only PFAS actually detected was trifluoroacetic acid, a substance that does not appear on the European regulatory PFAS list at all. Trifluoroacetic acid, usually abbreviated TFA, is the smallest member of the perfluoroalkyl acid family, with just a single carbon atom in its chain. Its ultrashort structure gives it unusual behavior in water: it is extremely mobile, essentially non-degradable, poorly removed by conventional drinking water treatment including activated carbon filtration and reverse osmosis under typical operating conditions, and it is not retained by the natural attenuation processes that can slow longer-chain compounds. Environmental scientists have warned in recent years that TFA is accumulating irreversibly in the global water cycle, with atmospheric degradation of refrigerant gases and fluorinated pesticides identified as substantial diffuse sources alongside industrial emissions.

The concentrations the researchers measured reveal a striking geographic pattern. Trifluoroacetic acid was systematically found in bottled waters from France, Belgium, and Morocco, with mean concentrations of 461 plus or minus 322 nanograms per liter, 438 plus or minus 178 nanograms per liter, and 74 plus or minus 12 nanograms per liter respectively. In Italy, the compound appeared in two brands at 350 plus or minus 49 and 88 plus or minus 16 nanograms per liter, while everywhere else in the survey concentrations remained below 50 nanograms per liter. The French figures are particularly notable because the mean of 461 nanograms per liter, with considerable variability between brands, represents concentrations several times higher than the cumulative regulatory limit that applies to the twenty regulated PFAS, even though TFA itself is not covered by that limit. The wide standard deviation for France indicates that some individual brands carry substantially more TFA than others, pointing to differences in the vulnerability of the aquifers and springs from which the water is drawn.

Why does TFA dominate where the regulated compounds do not? The answer lies in the chemistry and in the sources. The longer-chain PFAS that regulators have prioritized tend to bind to soils and sediments, move slowly through aquifers, and originate from relatively localized industrial and firefighting sources. TFA, by contrast, is generated continuously and diffusely. Hydrofluorocarbon and hydrofluoroolefin refrigerants, introduced as replacements for ozone-depleting substances, break down in the atmosphere to yield TFA that then falls with rain and snow. Certain pesticides degrade to trifluoroacetate in soils and leach into groundwater. Because these sources are distributed across entire regions rather than concentrated at a few discharge points, even well-protected aquifers used for bottling can carry measurable TFA loads. Studies in China have documented a seventeenfold increase in TFA in landscape waters around Beijing over a single decade, and researchers in Germany have identified ultrashort-chain PFAS as prevalent, overlooked, difficult to remove, and unregulated contaminants in the sources of drinking water.

The health implications of the measured TFA levels remain an open scientific question, and the study’s authors are careful not to overstate them. TFA has historically been regarded as one of the less toxic members of the PFAS family, and there is no drinking water limit for it in most jurisdictions. Yet the lack of a limit reflects a gap in the regulatory framework rather than a demonstrated absence of risk. The compound’s extreme persistence means that whatever enters aquifers now will remain there indefinitely, and environmental concentrations are rising globally. Some recent assessments have called for a more precautionary approach precisely because exposure is universal, irreversible on human timescales, and growing. The finding that a bottled water product, which consumers often choose specifically to avoid perceived contaminants, can carry hundreds of nanograms per liter of an unregulated fluorinated acid underscores how far the regulatory net still falls short of the actual chemical landscape.

The authors conclude that their findings highlight the need to include trifluoroacetic acid in bottled water monitoring, and that recommendation carries practical weight. Monitoring programs built around the twenty-compound European list would have reported every sample in this study as essentially clean, since nothing regulated was quantifiable. Only the broader 65-compound screen revealed the TFA signal. As regulators in Europe and elsewhere consider how to handle ultrashort-chain PFAS, studies like this one provide exactly the kind of occurrence data needed to set meaningful thresholds. The work also demonstrates the value of international collaborative networks, with the research supported by partnerships among universities in Besançon, Bari, Bucharest, Xi’an, and Sinaloa under a multi-year project running through 2029.

For consumers, the practical takeaway is measured rather than alarming. The regulated PFAS burden in the bottled waters tested is low, and the TFA levels, while notable, come with no established health-based limit to breach. What the study changes is the frame of the conversation. It shows that the forever chemicals problem is not confined to industrial river basins and contaminated municipal supplies, but has reached even the protected underground sources of premium bottled water through the diffuse, atmospheric, and agricultural pathways of the smallest PFAS molecule. It also shows that regulatory lists, however carefully constructed, can create blind spots: a water can comply fully with the law while still carrying a fluorinated compound at concentrations an order of magnitude above the legal threshold for its regulated cousins. Closing that gap between what is regulated and what is actually in the bottle is, the authors argue, the next necessary step in protecting drinking water quality worldwide.

Subject of Research: Occurrence of per- and polyfluoroalkyl substances, including trifluoroacetic acid, in bottled water from 11 countries

Article Title: Per- and poly-fluoroalkyl substances in bottled water samples from France, Italy, Belgium, Romania, Portugal, Lithuania, Georgia, Morocco, United States, Mexico, and China

Article References: Crini, G., Angonin, L., Mongioví, C., Elaissaoui, Z., Picos-Corrales, L. A., Rousseau, J., Bradu, C., Lichtfouse, E., Ansell, G. K., Grzymsky, G., & Lacalamita, D. (2026). Per- and poly-fluoroalkyl substances in bottled water samples from France, Italy, Belgium, Romania, Portugal, Lithuania, Georgia, Morocco, United States, Mexico, and China. Environmental Chemistry Letters. https://doi.org/10.1007/s10311-026-01929-9

Image Credits: AI Generated

DOI: 10.1007/s10311-026-01929-9

Keywords: PFAS, trifluoroacetic acid, bottled water, drinking water, forever chemicals, ultrashort-chain PFAS, European Drinking Water Directive, water contamination, environmental chemistry, TFA, water quality monitoring, groundwater