If your water report shows PFAS contamination - or you just want to be safe - choosing the right filter matters more than usual. Most basic pitcher filters won't touch PFAS. Some expensive systems remove 99%+. The difference comes down to the filtration technology and whether it's been independently tested.
Here's what actually works, what doesn't, and how to choose.
Which filter technologies remove PFAS?
Reverse osmosis (RO) - most effective
Reverse osmosis systems push water through a semi-permeable membrane with pores small enough to block PFAS molecules. Well-designed RO systems remove 90–99% of PFOA, PFOS, and other PFAS compounds. They're the gold standard for PFAS removal at home.
The catch: RO systems waste water (typically 2–4 gallons for every gallon of filtered water), they're slower than other filters, and they strip beneficial minerals along with contaminants. Most are installed under the kitchen sink and only filter water at that one tap - not the whole house.
Expect to pay $150–$400 for a quality under-sink RO system, plus $50–$100/year for replacement filters and membranes.
Granular activated carbon (GAC) - effective for some PFAS
Activated carbon filters work by adsorption - PFAS molecules stick to the carbon surface as water passes through. GAC filters are effective at removing longer-chain PFAS compounds like PFOA and PFOS (typically 70–90% removal), but less effective for shorter-chain PFAS like GenX and PFBS.
The key factor is contact time. Whole-house GAC systems with large carbon beds perform much better than small pitcher or faucet-mounted filters, which don't give the water enough time in contact with the carbon. A standard Brita pitcher, for example, has not been NSF-certified for PFAS removal.
Ion exchange resins - specialized option
Anion exchange resins specifically target negatively charged PFAS molecules. These systems can be highly effective (90%+) but are less common in residential settings. They're more often used in municipal treatment plants. Some whole-house systems combine ion exchange with activated carbon for comprehensive PFAS removal.
What doesn't work
Standard sediment filters, UV purification, water softeners, and boiling do NOT remove PFAS. Basic carbon pitcher filters (like standard Brita or PUR) have not been demonstrated to effectively remove PFAS, though some newer pitcher filters with specialized media are now seeking NSF P473 certification.
The certification that matters: NSF P473
NSF/ANSI P473 is the specific testing protocol for PFAS removal. A filter certified to P473 has been independently verified to reduce PFOA and PFOS to below 70 parts per trillion (the previous EPA advisory level). With the new EPA MCLs of 4 ppt for PFOA and PFOS, look for filters that demonstrate removal to those lower levels.
Don't trust marketing claims alone - check for actual NSF P473 certification, or look for the filter's test data showing specific PFAS reduction percentages.
Our recommendations by situation
PFAS detected in your water report: An under-sink reverse osmosis system is your best bet. It handles all PFAS compounds effectively and gives you clean drinking water without the cost of whole-house treatment.
PFAS likely but not tested (older system, near known contamination): A quality activated carbon filter certified to NSF P473 is a reasonable precaution. Whole-house GAC systems provide more protection than point-of-use filters.
Just want general peace of mind: A multi-stage under-sink filter with both activated carbon and a membrane component will address PFAS along with other common contaminants.
Check your water on ClearWater to see whether your system has been tested for PFAS and what was found.