Does Reverse Osmosis Remove PFAS?

In testing it has done best. In a 2020 Duke University and North Carolina State University study of filters in people’s homes, reverse osmosis and two-stage filters reduced PFAS levels, including GenX, by 94 percent or more. Duke’s Heather Stapleton said all of the under-sink reverse osmosis and two-stage filters achieved near-complete removal of the PFAS they tested for.

Other filters were less predictable. The same study found activated carbon filters removed 73 percent of PFAS on average but varied greatly, from complete removal to no reduction at all, and in four of the six whole-house carbon systems tested, levels of some PFAS increased after filtration. NC State’s Detlef Knappe said under-sink reverse osmosis was the most efficient system tested, but costs much more than other point-of-use filters.

The EPA describes reverse osmosis as a process that forces water through an extremely thin barrier that separates chemicals from the water. It tells shoppers to check the packaging for NSF/ANSI 53 or NSF/ANSI 58 certification for PFAS reduction, cautions that as of April 2024 those certifications did not yet show a filter removes PFAS down to its new drinking water standard, and says filters are only effective if maintained according to the manufacturer’s instructions. It also says that if PFAS in your water have not been measured, or are below federal limits, a filter may not be useful to you.

Sources checked September 15, 2026. Every point below links the page it came from.

The sources behind this answer

  • Independent testIn a 2020 Duke University and NC State study of home filters, reverse osmosis and two-stage filters reduced PFAS levels, including GenX, by 94 percent or more, though few two-stage filters were tested. Duke University via EurekAlert! ↗
  • Independent testThe same study found activated carbon filters removed 73 percent of PFAS on average, with results ranging from complete removal to no reduction. Duke University via EurekAlert! ↗
  • Independent testIn four of the six whole-house systems using activated carbon filters, PFSA and PFCA levels increased after filtration, the researchers reported. Duke University via EurekAlert! ↗
  • StudyNC State’s Detlef Knappe said the under-sink reverse osmosis filter was the most efficient system for removing the PFAS they tested, but costs much more than other point-of-use filters. Duke University via EurekAlert! ↗
  • Government sourceThe EPA describes reverse osmosis as a process that forces water through an extremely thin barrier that separates chemicals from the water. US EPA ↗
  • Regulatory filingThe EPA tells shoppers to check packaging for NSF/ANSI 53 or NSF/ANSI 58 certification for PFAS reduction, and cautions that as of April 2024 those certifications did not yet show a filter removes PFAS down to its new drinking water standard. US EPA ↗
  • Government sourceThe EPA says filters are only effective if maintained according to the manufacturer’s instructions, and that if PFAS have not been measured in your water or are below federal limits, a filter may not be useful to you. US EPA ↗

Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.

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