How to Check a Water Filter Is Certified to Reduce PFAS
1. Find out what is in your water
On a public supply, ask your water utility what it has measured for PFAS, or ask it to test; this is the first step US EPA suggests. On a private well, test regularly: EPA points well owners to their state's laboratory certification program to find a lab certified for PFAS analysis (EPA methods 533 and 537.1). Note which compounds the result names, such as PFOA and PFOS, because a filter's certification names compounds too.
2. Read the claim, not just the standard
EPA's advice is to look on the label for certification under NSF/ANSI 53 or NSF/ANSI 58 for PFAS reduction. Standard 53 covers activated-carbon and anion-exchange devices; standard 58 covers reverse-osmosis systems. A filter can be certified to NSF/ANSI 53 for something else, such as lead, so the certification has to name PFAS reduction, and EPA advises checking that it covers the type of PFAS you are trying to remove.
3. Confirm it in the certifier's own listing
Search the exact model number in the certifier's directory, and check that the listing names the PFAS compounds, such as PFOA and PFOS, or the "Total PFAS" claim NSF introduced in its 2022 update: PFOA, PFOS, PFHpA, PFHxS, PFNA and PFBS counted together, with the combined limit lowered from 70 to 20 parts per trillion. NSF's older protocol P473 has been retired; its products now appear under NSF/ANSI 53 or 58. EPA lists five certification bodies with searchable product listings:
- NSF
- UL
- WQA (Water Quality Association)
- CSA Group
- IAPMO R&T
4. Know what a certificate does not promise
EPA notes that the certification standards for PFAS filters, as of April 2024, do not yet show that a filter will reduce PFAS to the limits EPA has since set for drinking water: 4.0 parts per trillion each for PFOA and PFOS. A 2026 EPA proposal would give water systems until April 2031 rather than April 2029 to meet those limits; the limits themselves stay. Results also differ by filter type: in a 2020 study of North Carolina homes, under-sink reverse-osmosis and two-stage filters removed nearly all PFAS tested, while pitcher, faucet and other carbon filters removed about 60–70% of long-chain and about 40% of short-chain PFAS, and four of eight whole-house carbon systems raised PFAS levels.
5. Keep it working
EPA's warning is plain: filters are only effective if they are maintained according to the manufacturer's instructions for how long the filter or membrane lasts. Note the replacement interval from the listing or the manual and put it in your calendar. Reverse-osmosis systems also send about one gallon of water to the drain for every gallon they treat.
Where this applies
These are US certification standards and US EPA limits. Outside the United States, ask your water supplier what it measures and which certifications your national authority recognises.
Sources
- US EPA — Identifying drinking water filters certified to reduce PFAS (updated 18 November 2025) · read 2026-10-02
- US EPA — Meaningful and achievable steps you can take to reduce your risk (updated 14 July 2026) · read 2026-10-02
- US EPA — PFAS drinking water laboratory methods (updated 24 April 2026) · read 2026-10-02
- US EPA — Proposed PFOA and PFOS compliance extension rule (updated 23 July 2026) · read 2026-10-02
- NSF — Forever chemicals: the advancement of filtration standards (27 September 2024) · read 2026-10-02
- Herkert et al., Assessing the effectiveness of point-of-use residential drinking water filters for PFASs, Environmental Science & Technology Letters 2020, DOI 10.1021/acs.estlett.0c00004 · read 2026-10-02