Critical Research Journal | Graham Wilson

In an area known to have exceptionally high levels of PFAS in local groundwater (43000 times the recommended safe-levels), and where the mains water supply is fed from aquifers immediately beneath an air-force base fire training area, does it make sense to switch to bottled water as a short-term precaution?

Obviously, this is a personal choice. Do you want to wait until better information is available? Do you consider that long-term health risks are low in your priorities (as many smokers do)? Are you someone who is particularly lifestyle aware, who makes other food and drink related choices for health reasons?

However, for most of us, the simple answer is yes. As a short-term precaution, switching to bottled water for drinking, tea, coffee, cooking water, and tooth-brushing makes sense while you seek hard evidence about the treated mains supply. So far, there is no proof that the tap water is unsafe, but the facts that we have about our supply do create a clear source-pathway-receptor concern: a known PFAS source, extreme groundwater results, an aquifer pathway, and a drinking-water receptor.

The key point is that groundwater contamination is not the same as tap-water contamination. Mains water may be blended, treated, drawn from a different borehole, or monitored before supply. So far, however, Thames Water have been very limited in their response to questions.

The Drinking Water Inspectorate (DWI) says water firms must ensure water is wholesome, but England and Wales still lack a statutory PFAS limit. The DWI instead uses a tiered guidance system, now focused on the summed level of 48 PFAS, with 100 ng/L treated as a key action level. The Royal Society of Chemistry has argued for tighter controls, including 10 ng/L for any single PFAS and 100 ng/L for total PFAS. (Drinking Water Inspectorate)

The level measured in Gallos Brook recently – 43,000 times the recommended safe level – is so high that it justifies caution even before tap-water proof exists.

In case, anyone has missed the news in the last few months, air-force fire training areas are a well-known source of PFAS, due to historic use of aqueous film-forming foams. PFAS are persistent, mobile in water, and linked in the evidence base to harms that include effects on immunity, cholesterol, liver function, thyroid function, pregnancy outcomes, and some cancers. The US EPA now sets legally enforceable drinking-water limits of 4 ng/L for PFOA and PFOS, with 10 ng/L limits for several other PFAS. (US EPA)

Bottled water is not a perfect answer. PFAS have been found in some bottled waters, and bottled water brings cost, plastic waste, and microplastic concerns. A 2024 study reported PFAS in both tap and bottled water samples from the UK and China, with PFOA and PFOS detected in over 99% of bottled-water samples from 15 countries (University of Birmingham). Even so, bottled water from a source outside the suspect aquifer is a rational temporary measure when local groundwater contamination is extreme.

For the short term, using bottled water for all water that is swallowed, especially for children, pregnant people, and anyone with immune, thyroid, kidney, liver, or cancer risk concerns. Don’t worry much about showering or hand-washing unless official advice changes, because the main concern for PFAS in water is ingestion.

Boiling water does not remove PFAS – in fact, the opposite as it can concentrate them.

Is any bottled water likely to be safer, and is there any difference between spring water, mineral water, branded, and own label water from supermarkets?

Yes, some bottled water is likely to be safer than your local tap water as a short-term step, but no ordinary bottled-water label proves that it is PFAS-free. The safest choice would be water with a recent batch or source test showing low or non-detect PFAS. In normal shop terms, the next best rule is to choose water bottled from a named source outside the suspect catchment, rather than water with vague branding.

The legal labels matter, but not as much as the source. Natural mineral water has the tightest identity. It must come from an officially recognised underground source, keep its “original purity”, have a stable composition, and use only a small set of permitted treatments. The producer must gather safety and stability data, and Defra lists recognised UK natural mineral waters by source and place of exploitation. (GOV.UK) This makes natural mineral water more traceable, though it does not mean zero PFAS.

Spring water also comes from an underground source, but the regulatory status is less distinctive than natural mineral water. It may be a sound choice if the label names the spring or borehole and the source sits far from known PFAS sites. Bottled drinking water is a broader class. It may be treated water from various sources. That could be safer if it has been treated by reverse osmosis or high-grade activated carbon, but the label may not tell you enough.

Branded water is not always safer than supermarket own-label water. Some own-label waters come from recognised sources and are bottled by the same large suppliers that bottle branded products. For example, the current UK list includes recognised natural mineral waters such as Ashbeck, Aqua Pura, Celtic Spring, Radnor Hills, and Waitrose Welsh Spring, each with its named place of exploitation. (GOV.UK) The real test is not price or brand; it is source, treatment, and PFAS data.

There is also a limit to what bottled water can solve. A 2024 study found PFAS in both tap and bottled water, with PFOA and PFOS detected in over 99% of bottled-water samples sourced from 15 countries. It also found wide variation across samples. (University of Birmingham) This means bottled water may reduce a local high-risk exposure, but it should not be treated as pure water.

For your short-term purpose, I would choose in this order: natural mineral water from a clearly named distant source, then spring water from a clearly named distant source, then treated bottled drinking water only if the treatment is stated. I would not rely on “British”, “pure”, “mountain”, “still”, or “premium” as safety terms. I would also avoid local or regional bottled water if its source lies in the same broad aquifer system as the air-force base.

For the options we discussed earlier, Celtic Spring and Radnor Hills have named Welsh sources on the recognised natural mineral water list, which gives them traceability. Highland Spring has stronger packaging claims, but for PFAS risk the more relevant question is whether it publishes current source-water PFAS tests. Until such data are in hand, a cheap named-source natural mineral water is a reasonable short-term precaution.

Does the packaging make a difference? Water comes in glass bottles, cans, plastic lined boxes, and in a few cases in a carton.

Yes, packaging can make a difference, but probably less than the source water itself when the chief concern is PFAS. The best short-term choice would still be a named-source water from outside the suspect aquifer, with the least complex packaging.

Glass is usually the most inert main container. It does not shed plastic from the body of the bottle, and it has low chemical migration compared with many other materials. The main caveat, though, is the closure. A 2025 French study found that some drinks in glass bottles had higher microplastic counts than plastic bottles or cans, probably due to polyester-based paint on metal caps. The glass itself was not the source. (anses.hal.science)

PET plastic bottles are food-grade and widely used, but bottled water in plastic tends to carry more microplastic and nanoplastic concern than tap water in many studies. A review of 21 studies found microplastics in both tap and bottled water, with higher levels in bottled water. (PMC) This does not mean PET water is acutely unsafe. It means PET is a less ideal long-term default, especially if bottles are stored warm, reused, crushed, or left in sunlight.

Cans are not bare metal inside. They almost always have a polymer lining to stop corrosion and taint. That lining may reduce metal leaching, but it adds another food-contact layer. It is not an obvious gain over glass or PET for water, unless the firm publishes good test data. The same point applies to boxed water and cartons. They look paper-based, but they usually contain layers of board, plastic, and sometimes aluminium. They are complex packs, and their safety depends on the liner and sealant, not on the word “carton”.

For PFAS, the position is more awkward. UK food-contact material law requires packaging to be safe for food use, but campaign and policy sources note that UK rules still do not set broad limits for most PFAS in food-contact materials. (Food Standards Agency) The EU’s new packaging rules move further by restricting PFAS in food-contact packaging above set thresholds, but that does not yet give you a simple UK shop-shelf guarantee. (Environment)

A pragmatic ranking would be: glass bottle with a plain screw cap, then large PET bottle from a named distant source, then can, then carton or boxed water. For short-term PFAS caution, you can buy large 5L PET or glass from a traceable source rather than small bottles, cans, or cartons. Large bottles reduce the amount of packaging contact per litre and reduce waste.

Have we switched?

Yes. As someone who believes very strongly in the importance of evidence, as a short-term solution, we have switched to spring-water from Scotland in 10l bags within a cardboard box.

After a lot of searching online, we settled on these from Purely Scottish. We chose them because the bags are double-lined and made from a plant-based plastic substitute. This means that they can be separated and used to line our silver food-waste bin, from which they go off to be industrial biodegraded. They are therefore one of the better options for the environment.

Purely Scottish water works out at about 68p per litre. If you want to switch but prefer a cheaper, plastic container, option then the best on the market right now is Celtic Spring in 5l boxes from Iceland at 28p per litre. Waitrose Own Label in 5l boxes is 34p per litre. Highland Spring, which is very popular, is £1.40 per litre.

References

Chaïb, I., et al. (2025). Microplastic contaminations in a set of beverages sold in France. Journal of Food Composition and Analysis. (anses.hal.science)

Department for Environment, Food and Rural Affairs. (2026). UK natural mineral waters recognised in the UK: List of products. GOV.UK. (GOV.UK)

Department for Environment, Food and Rural Affairs. (2020). Natural mineral water: Rules for local authorities. GOV.UK. (GOV.UK)

Drinking Water Inspectorate. (2026). PFAS and forever chemicals. https://www.dwi.gov.uk/pfas-and-forever-chemicals/

European Commission. (2026). Packaging waste. (Environment)

Food Standards Agency. (2018). Food contact materials regulations. (Food Standards Agency)

Gambino, I., et al. (2022). Occurrence of microplastics in tap and bottled water. International Journal of Environmental Research and Public Health. (PMC)

Royal Society of Chemistry. (2023). Cleaning up UK drinking water. https://www.rsc.org/policy-and-campaigning/sustainability/cleaning-up-uk-drinking-water

Royal Society of Chemistry. (2023). RSC challenges UK Government to reduce PFAS levels in British water. https://www.rsc.org/news/2023/october/rsc-challenges-uk-government-to-reduce-pfas-levels-in-british-water-as-research-highlights-serious-health-risks-posed-by-%E2%80%98forever-chemicals%E2%80%99

United States Environmental Protection Agency. (2024). Final PFAS national primary drinking water regulation. https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas

University of Birmingham. (2024). Forever chemicals found in bottled and tap water from around the world. (University of Birmingham)

(c) 2026 Graham Wilson. This work is licensed under CC BY-NC 4.0. To view a copy of this license, visit creativecommons.org