Unless noted, specs and performance figures below come from the manufacturers.

The short version

PFAS are industrial chemicals that were designed to shrug off heat, water, and grease. That toughness is the problem. They barely break down in the environment or in your body, so small exposures add up over years. In 2024 the EPA set the first national drinking water limits for six of them. This page explains what PFAS are, what the EPA says about the health risk, what the limits are and where they stand now, how to check your own water, and which filter technologies the EPA says can reduce them. For product picks, see our guide to the best water filter for PFAS.

What PFAS actually are

PFAS stands for per and polyfluoroalkyl substances. The name describes the chemistry: carbon chains loaded with fluorine, which makes the chemicals extremely stable and slippery. There are thousands of different PFAS, and they have been used in industry and consumer products since the 1940s because they repel oil and water and resist heat.

Two members of the family get most of the attention. PFOA and PFOS are the most widely used and the most studied, and they are the two the federal limits focus on. Both have largely been replaced in United States manufacturing by newer PFAS, but replacement is not removal. The older chemicals are still in soil and groundwater, and they move slowly.

The key fact for a homeowner is persistence. Many PFAS break down very slowly and can build up in people, animals, and the environment over time. That is why regulators care about very small amounts, and why the limits below are measured in parts per trillion. A part per trillion is a thousand times finer than a part per billion.

Where PFAS come from

The EPA lists the common places PFAS show up. They are in nonstick cookware, waterproof and stain resistant fabrics, grease resistant food packaging such as fast food wrappers and microwave popcorn bags, and some cosmetics and cleaning products. The heavy sources are industrial. Firefighting foam used at airports, military bases, and training sites is a major one, along with factories that make or use PFAS, landfills and waste sites, and farm fields treated with treated sewage sludge used as fertilizer.

From those sources PFAS wash into soil, groundwater, and rivers. Drinking water is one exposure route among several, which include food, dust, and the products themselves. The EPA notes that drinking water can be a significant share of a person's total PFAS exposure, which is why it is the route a homeowner can actually do something about.

What the EPA says about health risk

The EPA's summary of the research is careful, and this page keeps it that way. Studies show that exposure to certain levels of some PFAS may lead to reproductive effects such as decreased fertility or increased high blood pressure in pregnant women, developmental effects or delays in children, increased risk of some cancers including prostate, kidney, and testicular cancers, a reduced ability of the immune system to fight infections including a reduced vaccine response, interference with the body's natural hormones, and increased cholesterol levels.

Two honest caveats belong with that list. First, there are thousands of PFAS and most studies cover only a few of them, so the evidence is deep for PFOA and PFOS and thin for the rest. Second, researchers are still working out how low level exposure over long periods affects people, especially children. The EPA set its health based goal for PFOA and PFOS at zero, which reflects its conclusion that there is no level of exposure to those two without risk. The enforceable limits sit above zero because they also account for what treatment can realistically achieve.

The federal limits, and where they stand now

In April 2024 the EPA finalized the first national drinking water regulation for PFAS. It set legally enforceable limits, called Maximum Contaminant Levels, for six PFAS:

Compound Enforceable limit
PFOA 4.0 parts per trillion
PFOS 4.0 parts per trillion
PFHxS 10 parts per trillion
PFNA 10 parts per trillion
HFPO-DA, known as GenX chemicals 10 parts per trillion
Mixtures of two or more of PFHxS, PFNA, HFPO-DA, and PFBS Hazard index of 1

The rule runs on a schedule. Public water systems have until 2027 to complete initial monitoring, and they must give the public information on the PFAS levels in their drinking water beginning in 2027. Systems that find levels above the limits then have to install treatment, with the original deadline set at 2029.

Where the rule stands now is less settled than the table suggests. In 2025 the EPA announced it would keep the PFOA and PFOS limits and propose dropping the limits for PFHxS, PFNA, GenX, and the mixture measure, and in May 2026 it published proposed rules that would do that and would let systems request until 2031 to meet the PFOA and PFOS limits. Those changes are proposals, not final law. The monitoring and reporting schedule has not changed, and some states enforce their own PFAS limits regardless of what happens at the federal level. The practical takeaway for a homeowner: the numbers are coming either way, and PFOA and PFOS at 4.0 parts per trillion are the standards most likely to survive.

How to check your own water

Start with your water provider. Many public systems already have PFAS test results available, and the EPA advises contacting your local provider to find out which PFAS, if any, are in your drinking water. A separate national program, the fifth round of unregulated contaminant monitoring, tested public water systems for 29 PFAS between 2023 and 2025. Systems have to tell customers those results are available and report what they found, at or above the reporting level, in their annual water quality report.

Our own tool pulls the federal record for your city system. See what is in my city's water for violations and contaminant history. From 2027 onward, PFAS levels from the new rule's monitoring join the annual water quality report, so this gets easier every year.

If you are on a private well, nobody tests your water for you. The EPA treats wells as part of the PFAS picture, and a certified lab test is the only way to get your own number. A test result, from a report or a lab, is what turns the rest of this page from background reading into a buying decision.

What actually removes PFAS

The EPA's home filter guidance names three technologies that can be effective at reducing PFAS:

Activated carbon. These filters use carbon to trap chemicals as water passes through them. This covers the granular activated carbon in whole house tanks and the carbon blocks in smaller filters. Carbon is strongest on the longer chain PFAS such as PFOA and PFOS, and it is the technology inside almost every whole house system we review.

Reverse osmosis. This process forces water through an extremely thin barrier that separates chemicals from the water. Osmosis systems sit under a sink or on a counter and treat drinking and cooking water rather than the whole house. The EPA fact sheet treats them as one of the effective options, and PFAS certification is deepest in this category.

Ion exchange. The resins are tiny beads that act like magnets, attracting and holding the contaminated material so it does not pass through with the water. This is the same basic technology as a water softener, aimed at different targets, and it shows up more in municipal treatment and specialty systems than in mainstream whole house filters.

What the EPA says to check, whichever technology you choose, is certification. Look on the packaging for certification to NSF/ANSI 53 for a carbon filter, or NSF/ANSI 58 for reverse osmosis, with a PFAS reduction claim attached. Certification by an independent body is the assurance that the filter works the way the manufacturer says it does. One honest caveat from the EPA itself: the current certification standards do not yet promise removal down to the new federal limits. Reducing PFAS is still worthwhile, but a certified filter is not a guarantee of water at or below 4.0 parts per trillion. Maintenance also matters. A filter that is not replaced on schedule stops protecting you.

What this means for the systems we review

PFAS is where the gap between claims and certification is widest in whole house filtration, and our coverage keeps the two separate.

SpringWell states that its CF1 reduces PFAS, including PFOA and PFOS. That is a manufacturer claim. The complete system is not NSF certified for PFAS, and no certifier lists it for PFAS reduction, although its filter media parts carry NSF/ANSI 42 and 53 certifications and independent lab testing by Quality Water Lab has verified other performance claims such as disinfection byproduct reduction. We cover the detail in our SpringWell review.

The Aquasana Rhino, the best known whole house tank in the category, carries no PFAS certification at all. Aquasana puts its certified PFAS reduction in a different model, the HealthShield. Our separate page answers the common question directly: does Aquasana remove PFAS?

The honest bottom line

PFAS in drinking water is a real, regulated problem with an unfinished rulebook. The two chemicals that matter most, PFOA and PFOS, have enforceable limits of 4.0 parts per trillion, monitoring completes by 2027, and results are about to become much easier for homeowners to see. If your water report shows PFAS, the fix the EPA points to is a certified filter using activated carbon, reverse osmosis, or ion exchange. If your report shows none, a filter bought for PFAS alone may not be useful to you. Start with the number, then read our best water filter for PFAS guide for the certified picks.