PFAS in drinking water

PFAS, short for per- and polyfluoroalkyl substances, are a group of thousands of chemicals that have been used in industry and consumer products since the 1940s. They repel oil and water and resist heat, which made them useful in nonstick cookware, food packaging, waterproof clothing, stain-resistant furniture and firefighting foam. They also break down very slowly. Because they're so widespread and long-lasting, PFAS turn up in water, soil, air and fish, and in the blood of people and animals worldwide.

Studies have shown that exposure to some PFAS may be linked to harmful health effects. Drinking water can be a large share of a person's total exposure, so it's a good place to start.

The federal limits

The federal drinking water limit for PFOA and PFOS is 4.0 parts per trillion each. A 2024 EPA rule also set limits for four other PFAS, and in May 2026 the EPA proposed rescinding those four.

Finding out about your water

Many public water systems already have PFAS test results. Ask your water provider which PFAS, if any, are in your water. The EPA also has a database of water system test results and a map-based tool showing which systems have been tested. Your state's environmental agency or health department may have more on PFAS where you live. Reading your water system's annual quality report walks through the report itself.

If PFAS haven't been measured in your water, or were measured below the federal limits, a filter may not help.

If you use a home filter

Not every filter reduces PFAS. Look on the packaging for certification to NSF/ANSI 53 or NSF/ANSI 58 for PFAS reduction. If you're unsure, the certification body's online product directory shows whether a model is certified for PFAS such as PFOA and PFOS. As of April 2024, these certifications don't yet show that a filter brings PFAS down to the EPA's new limits, though any reduction lowers your exposure.

Home filters that reduce PFAS include:

• Granular activated carbon, which traps the chemicals as water passes through
• Reverse osmosis, which forces water through a very thin barrier that separates out the chemicals
• Ion exchange resins, small beads that attract the contaminants and hold onto them

They range from pitchers to faucet units to whole-house systems. A filter only works if it's maintained. A cartridge left in past the maker's replacement schedule can raise your exposure.

An annotated example

What to do next

Ask your water provider for its PFAS test results, or look them up in its annual water quality report. If you use a filter, check its packaging for NSF/ANSI 53 or 58 certification for PFAS, and replace the cartridge on the maker's schedule.