Does boiling tap water reduce PFAS? What public bodies and research say
The U.S. state of New Jersey explains that boiling “does not remove” PFAS. In research too, boiling reduced PFOS and PFOA by only a little over 10%; the large reductions were for some more volatile PFAS and with activated carbon filtration. We found no document from a Japanese public body that clearly states the effect of boiling. We separate what is known from what is not.
Short answer
The New Jersey Department of Health explains that “PFAS are not removed from water by boiling.” The U.S. Agency for Toxic Substances and Disease Registry (ATSDR) says “most PFAS do not evaporate,” so if only the water evaporates, in theory the PFAS become slightly more concentrated.
On the other hand, a study by the University of Birmingham and others (2024) tested laboratory water spiked with PFAS and reported that boiling alone reduced five substances including PFOS and PFOA by only 11–14%, while the more volatile FOSA fell by 61% and four others by more than 86%. A pitcher-type activated carbon filter reduced all 10 substances by 81–96%. The “50–90% reduction” in the abstract is an estimate of combined exposure to the 10 substances: about 50% with boiling and more than 90% with activated carbon.
We found nothing in the Q&As of Japan’s Ministry of the Environment, the FSCJ or water bureaus that clearly states the effect of boiling. The methods whose performance in reducing PFOS and PFOA has been tested are activated carbon and reverse osmosis (RO) water filters.
What public bodies say: “boiling doesn’t remove it”
| Body | Explanation |
|---|---|
| New Jersey Department of Health | These PFAS are not removed from water by boiling. Exposure from showering, bathing, laundry and dishwashing is not significant |
| Japan (Ministry of the Environment, FSCJ, and the Tokyo, Kobe and Saitama water bureaus) | No document clearly stating the effect of boiling was found |
- The U.S. ATSDR writes that “most PFAS do not evaporate.” If only the water evaporates and the PFAS remain, they become more concentrated in theory.
What research reports: boiling greatly reduces only some PFAS
- Gao et al. 2024 (University of Birmingham, Southern University of Science and Technology in China and others, ACS ES&T Water) examined 10 PFAS in tap water from the UK and China and in bottled water from 15 countries. The total of the 10 was 2.7 ng/L in UK tap water and 9.2 ng/L in China.
- In this study, boiling alone reduced PFOA, PFNA, PFOS, PFBS and PFHxS by 11–14%, FOSA by 61%, and four including EtFOSA by more than 86%. Activated carbon (pitcher type) reduced all 10 by 81–96%, and activated carbon followed by boiling by 81–99.6%. The test used not tap water but ultrapure water spiked with 5 ng/L of each.
- The abstract’s “boiling or activated carbon filtration can reduce it by 50–90%” is an estimate of combined exposure to the 10 substances, meaning about 50% with boiling and more than 90% with activated carbon. It does not mean that boiling halves PFOS and PFOA.
With an explanation that “in theory it becomes slightly more concentrated” and an experiment where “it fell by about 10%,” Urayomi writes neither “boil it and you have nothing to worry about” nor “boiling concentrates it to dangerous levels.”
Think of the purpose of boiling separately from PFAS
- Most reasons for boiling tap water are to deal with bacteria, or with residual chlorine and trihalomethanes. PFOS and PFOA are substances with different properties and can’t be thought of the same way.
- Most tap water values are nd (below the lowest measurable level) or a few ng/L. The first step is to look at your local value and compare it with the standard of 50 and the TDI.
If you want to reduce it: methods whose performance has been tested
- The U.S. EPA explains that granular activated carbon works well for long-chain PFAS such as PFOA and PFOS but less well for short-chain ones such as PFBS and PFBA. Reverse osmosis (RO) typically removes 90% or more of many PFAS, including short-chain ones.
- PFOS/PFOA claims on Japanese water filters follow a voluntary standard of the Japan Water Purifier Association (JWPA) (JWPAS B.210) and are not labeling items required by law. Testing uses water at 50 ng/L, and the volume of water until the removal rate falls to 80% is shown as the “rated volume (total filtered water).”
- Rated volumes and differences in type for each product are compared on the water filter page.
Sources
- New Jersey Department of Health fact sheet, “PFAS in Drinking Water”
- U.S. ATSDR, “PFAS: Human Exposure”
- Gao C et al. 2024, PFAS in tap water from the UK and China and bottled water from 15 countries (ACS ES&T Water 4(11):4881-4892)
- U.S. EPA, “Reducing PFAS in Drinking Water with Treatment Technologies”
- Ministry of the Environment, FAQ on PFAS
Last checked 2026.10.04 (against the original government documents and papers, collected and cross-checked in Gemini Notebook). Utility values are as in the national table; Urayomi sorted and summarized them.
Other explainers
- How was the “50 ng/L” standard set?
- How do you check PFAS in your local tap water?
- What about PFAS in mineral water and bottled water?
- Does PFAS enter your body in the shower or bath?
- How does PFAS affect the body?
- What happened in areas with high values?
- High in rivers or groundwater = high in tap water?