Do water filters remove PFAS?

First, find out if you need one

EPA's own advice starts with your water, not a product: find out which PFAS, if any, are in it. "If PFAS have not been measured in your water, or if PFAS have been measured but are below federal limits, a filter may not be useful to you."

Most people on public water can find out. EPA's UCMR 5 program tested nearly every utility serving more than 3,300 people for 29 PFAS, and TapBuff shows each utility's results against the legal limit and the health goal.

The limits, and where they stand

EPA set the first national PFAS limits in April 2024. PFOA and PFOS have a legal limit of 4.0 ppt each and a health goal of zero. Three more PFAS, and a combined measure for mixtures, were also given limits. In May 2026 EPA proposed rescinding those three and the mixture measure, and proposed giving utilities until 2031 to meet the PFOA and PFOS limits. The PFOA and PFHxS pages carry the current status, with dates.

Three kinds of filter can work

EPA names three:

• Activated carbon. Carbon traps the chemicals as water passes through. Pitchers, faucet mounts, under-sink filters and whole-house systems all use it.
• Reverse osmosis. Water is forced through a very thin membrane that holds chemicals back. Under-sink and countertop systems.
• Ion exchange resins. Tiny beads that hold onto contaminants. Often paired with carbon.

The type tells you what is possible. The certification tells you what a specific product has been shown to do.

What to look for on the listing

Look for a PFAS reduction claim under NSF/ANSI 53, or under NSF/ANSI 58 for a reverse osmosis system, on a certifier's own listing. On NSF listings the claims read "PFOA Reduction," "PFOS Reduction" and "Total PFAS Reduction." NSF defines Total PFAS as seven compounds: PFOA, PFOS, PFHxS, PFNA, PFHpA, PFBS and PFDA. WQA words them as "Perfluorooctanoic Acid (PFOA)" and "Perfluorooctane Sulfonate (PFOS)."

You may still see "NSF/ANSI 473" on older boxes and websites. That was NSF Protocol P473. NSF folded it into 53 and 58 and retired it.

A claim under NSF/ANSI 42 or NSF/ANSI 401 alone does not cover PFAS.

What a certification can't promise yet

EPA is plain about the gap: "the current certification standards for PFAS filters (as of April 2024) do not yet indicate that a filter will remove PFAS down to the levels EPA has now set for a drinking water standard." NSF's PFAS claims are tested against a level above EPA's 4.0 ppt limits, and NSF says work to align its standard with EPA's rule is underway.

That does not make a certified filter pointless. EPA's advice is that "reducing levels of PFAS in your water is an effective way to limit your exposure." It means a certified claim is the best evidence available, not a guarantee of a number.

Replace it on schedule

EPA: "Not replacing a filter by the manufacturer's recommend schedule can increase your risk of exposure to PFAS." A spent carbon cartridge stops working. The maker rates each cartridge in gallons and months; whichever runs out first is the one that counts. The five-year cost calculator works out how often that is for your household, and what it costs.