It follows an earlier study in May, also by the European Pesticide Action Network (PAN Europe) and its members, that found "alarming" levels of PFAS chemicals in Europe's rivers, lakes and groundwater.
Widely used in everyday items like cosmetics, non-stick pans and fire extinguishers, PFAS long-life substances are highly durable products that can take centuries to break down.
Samples for this latest study, taken from bottled and tap water in 11 EU countries, detected the presence of TFA (trifluoroacetic acid).
A major source of TFA is degrading PFAS used in certain synthetic pesticides and cooling gases in refrigeration and air conditioning, among other applications.
The possible impact on human health of PFAS, and of TFA in particular, has been growing, but "surprisingly few toxicological studies are available", PAN Europe said.
The samples tested by the Water Technology Centre in Karlsruhe, Germany, found TFA in 34 of 36 tap water samples and in 12 of the 19 bottled mineral and spring waters.
TFA values in tap water ranged from "undetectable" to 4,100 nanograms/litre, with an average of 740 ng/L.
In mineral and spring waters, TFA values ranged from "undetectable" to 3,200 ng/L, with an average of 278 ng/L.
PAN Europe backed the proposal made by the Dutch National Institute of Public Health and the Environment to set a standard at 2,200 ng/L.
This "was set in such a way that the consumption of drinking water only fulfils 20 percent of the tolerable daily intake," PAN Europe said.
This threshold was exceeded in mineral water analysed in drinking water from Austria (4,100 ng/L), while in Paris, the tap water analysed contained 2,100 ng/L.
Under European Union rules, from 2026 all drinking water must not exceed 500 ng/L for all PFAS, and NGOs are demanding that TFA be added to the list.
An earlier decision to class TFA as "non-relevant" under EU pesticide regulations was "regrettable" considering its "toxicological profile still leaves many questions unanswered", the report in May said.
A recent study on rabbits and TFA exposure found birth defects in offspring, raising serious concerns about this chemical.
PAN Europe has called for urgent interventions to address this "political failure", starting with a "rapid ban" on PFAS pesticides and a rethink on the threat posed by individual chemicals like TFA.
