The three technologies that actually remove PFAS

Three technologies have been proven to remove PFAS from drinking water: granular activated carbon, reverse osmosis, and ion exchange resin.

Granular activated carbon, or GAC, is the most common technology in home filters. Carbon works through adsorption. PFAS molecules stick to the surface of the carbon particles as water flows through. GAC filters are affordable and widely available, but they have limits. The carbon eventually becomes saturated and stops working. How long that takes depends on how much PFAS is in your water and how much water you filter.

Reverse osmosis, or RO, pushes water through a semi-permeable membrane under pressure. The membrane's tiny pores let water molecules through but physically block PFAS and most other contaminants. RO systems are more expensive than carbon filters, but they remove a wider range of PFAS compounds more completely.

Ion exchange resin uses a chemical process to swap PFAS ions for harmless ions like chloride. As water passes through the resin, PFAS molecules are captured and replaced. Ion exchange is common in larger treatment systems and some specialized home filters. It works well for PFAS but is less common in consumer products than carbon or RO.

All three technologies work. The right choice depends on what's in your water, your budget, and how much water you need to treat.

NSF certifications: what to look for on the box

Not all water filters remove PFAS. The box might say "reduces contaminants" or "improves water quality" without actually being tested for PFAS. Look for specific NSF certifications.

NSF/ANSI 53 is the standard for filters that reduce specific health-related contaminants. If a filter is certified to NSF 53, check the fine print. The certification label or the manufacturer's data sheet must list "PFOA/PFOS" as a tested contaminant. NSF 53 alone is not enough. The PFAS claim must be explicit.

NSF/ANSI 58 is the standard for reverse osmosis systems. Again, look for "PFOA/PFOS" in the contaminant reduction claim. An RO system can be certified to NSF 58 without being tested for PFAS, so read the label carefully.

NSF/ANSI 401 covers emerging compounds like some pharmaceuticals and pesticides. It does NOT specifically certify PFAS removal. A filter with only NSF 401 certification may not have been tested for the PFAS in your water.

NSF/ANSI 42 certifies filters for taste, odor, and chlorine reduction. It has nothing to do with PFAS. If a filter only has NSF 42 certification, it will not remove PFAS.

The certification should also list which specific PFAS compounds the filter was tested against. Many filters are certified for PFOA and PFOS, the two most studied PFAS. Fewer are certified for shorter-chain compounds like PFBS, PFBA, or GenX. If your water contains those compounds, you need a filter that has been tested for them.

Pitcher and faucet filters

Pitcher filters and faucet-mount filters are the lowest-cost entry point for PFAS removal. A pitcher costs $25 to $45. Replacement filters cost $30 to $60 per year for a typical household. Faucet-mount filters cost $20 to $50 upfront and $50 to $100 per year for replacements.

These filters use activated carbon. Water flows through the carbon cartridge by gravity or tap pressure. If the filter is certified to NSF 53 for PFOA and PFOS, it will reduce those compounds to low levels.

Each filter cartridge has a rated capacity, usually 40 to 100 gallons. Once the carbon is saturated, the filter stops working. Performance drops sharply after the rated capacity is reached. You must replace the filter on schedule. If you forget, you are drinking unfiltered water.

Pitcher and faucet filters are practical for drinking and cooking water. They are not designed to filter large volumes. If you need filtered water for coffee, cooking, and drinking throughout the day, track your usage and replace filters before they expire.

These filters work well for PFOA and PFOS if properly maintained. They are less reliable for shorter-chain PFAS. Check the certification details before you buy.

Under-sink reverse osmosis

Under-sink RO systems cost more upfront, typically $150 to $400 installed, but they provide the most thorough PFAS removal available for home use. An RO system includes pre-filters to remove sediment and chlorine, the RO membrane that blocks PFAS, and a post-filter to improve taste. Annual filter and membrane replacement costs $50 to $100.

RO removes PFAS along with lead, arsenic, nitrates, and dissolved solids. The membrane blocks nearly all contaminants larger than a water molecule. For households with multiple water quality concerns, RO solves more than one problem.

The main drawback is water waste. Traditional RO systems send 2 to 4 gallons down the drain for every gallon of filtered water produced. Newer tankless systems are more efficient, wasting closer to 1 to 1. The wastewater goes to your sewer or septic system, not back into your drinking water.

RO systems are installed under the kitchen sink and connect to a dedicated faucet. Installation takes a few hours if you are comfortable with basic plumbing. Many retailers offer installation services.

Look for NSF/ANSI 58 certification with PFOA and PFOS listed in the contaminant claim. RO is more effective than carbon filters at removing shorter-chain PFAS like GenX and PFBS.

Whole-house systems

Whole-house filters treat water at the point where it enters your home, so every tap, shower, and appliance gets filtered water. A residential whole-house GAC system typically costs $1,000 to $3,000 installed. Annual maintenance, including carbon replacement, runs $100 to $300.

Whole-house systems make sense if your tap water is significantly contaminated and you want filtered water everywhere. You get PFAS-free water from the shower, the washing machine, and the ice maker.

But for most households, a whole-house system is more than necessary. PFAS exposure from bathing and showering is minimal. PFAS is not significantly absorbed through the skin, and it does not vaporize into steam you would inhale. Nearly all PFAS exposure comes from drinking water and food.

An under-sink filter for drinking and cooking water is more cost-effective for most families. You get the health benefit without the expense of filtering water you use to flush the toilet or water the lawn.

If you do install a whole-house system, choose one with NSF 53 certification for PFAS. Make sure the system is sized correctly for your household's water usage. An undersized system will exhaust the carbon quickly and stop removing PFAS.

What does NOT work

Some common water treatment methods do not remove PFAS.

Boiling water does not remove PFAS. Boiling kills bacteria and viruses, but PFAS does not evaporate. Boiling actually concentrates PFAS by reducing the volume of water.

Standard refrigerator filters and older pitcher filters without NSF 53 certification for PFAS do not remove PFAS. Many refrigerator filters are only certified to NSF 42 for taste and odor. Check the filter's certification before assuming it works.

Ultraviolet treatment kills bacteria and some viruses. It has no effect on chemical contaminants like PFAS.

Water softeners remove hardness minerals like calcium and magnesium. They do not remove PFAS.

Distillation can remove PFAS by boiling water and condensing the steam, but it is slow and impractical for daily household use. Distillation units are expensive and energy-intensive.

Quick cost comparison

Here is what you can expect to pay for PFAS filtration:

  • Pitcher filter: $25 to $45 upfront, $30 to $60 per year for replacement filters
  • Faucet-mount filter: $20 to $50 upfront, $50 to $100 per year for replacement filters
  • Under-sink reverse osmosis: $150 to $400 installed, $50 to $100 per year for replacement filters and membranes
  • Whole-house GAC system: $1,000 to $3,000 installed, $100 to $300 per year for carbon replacement and maintenance

These are typical ranges. Prices vary by region, retailer, and system capacity. Installation costs are higher if you hire a plumber.

The lowest upfront cost does not always mean the lowest long-term cost. A pitcher filter is cheap to buy but requires frequent replacement. An RO system costs more upfront but lasts years with basic maintenance.

Before you buy: verify your specific PFAS

Different filters are certified to remove different PFAS compounds. Before you buy, find out what is actually in your water.

Look up your water system on CheckYourWater or request a Consumer Confidence Report from your utility. The report will list detected contaminants and their concentrations. If your utility has tested for PFAS, the report will show which compounds were found and at what levels.

Match the compounds in your water to the compounds the filter is certified to reduce. If your water contains PFOA and PFOS, a filter certified for those two compounds will work. If your water contains shorter-chain PFAS like PFBS, PFBA, or GenX, check whether the filter has been tested for those specific compounds.

Reverse osmosis systems are generally more reliable than activated carbon for removing shorter-chain PFAS. The RO membrane physically blocks molecules, so it works across a wider range of PFAS types. Carbon filters are effective for longer-chain PFAS like PFOA and PFOS but may be less effective for newer compounds.

If your water has not been tested for PFAS, contact your utility and ask when testing will occur. The EPA's new drinking water standards require public water systems to monitor for PFAS starting in 2027. Until then, some utilities are testing voluntarily.

Filtering your water makes sense if PFAS has been detected above the federal limits: 4 parts per trillion for PFOA, 4 ppt for PFOS, 10 ppt for PFNA, 10 ppt for PFHxS, and 10 ppt for GenX. Even at lower levels, filtration reduces your exposure. But knowing what is in your water helps you choose the right filter and avoid paying for technology you do not need.