What Is PFAS and How to Remove It From Drinking Water

PFAS -- per- and polyfluoroalkyl substances -- have become one of the most widely discussed drinking water concerns in recent years, and for good reason. In April 2024, the EPA finalized the first-ever enforceable federal maximum contaminant levels for six PFAS compounds in drinking water, reflecting decades of research linking these chemicals to serious health outcomes.

Understanding what PFAS are, where they come from, and which filtration methods actually remove them is increasingly important for any homeowner evaluating their drinking water safety.

What PFAS Are and Why They Are Called "Forever Chemicals"

PFAS is an umbrella term covering thousands of synthetic chemical compounds that share a carbon-fluorine bond -- one of the strongest bonds in organic chemistry. This bond makes PFAS compounds extraordinarily stable: they do not break down naturally in the environment or in the human body.

They accumulate in soil, surface water, groundwater, food sources, and biological tissue over time. The term "forever chemicals" reflects this persistence -- once PFAS contaminate a water supply, they remain indefinitely without active remediation.

The two most studied PFAS compounds are PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate), both of which were used extensively in industrial applications including non-stick cookware coatings, stain-resistant fabrics, food packaging, and firefighting foam (AFFF). Industrial facilities, military bases, and airports that used AFFF are among the most significant sources of groundwater contamination.

PFAS Regulation: The 2024 EPA Standards

The EPA's April 2024 final rule established Maximum Contaminant Levels (MCLs) for six PFAS in public water systems:

Public water utilities have until 2027 to comply with these standards. This means water systems currently meeting older standards may still contain PFAS concentrations above the new MCLs until remediation infrastructure is completed. Private well owners are not covered by these regulations at all and are responsible for their own testing and treatment.

How to Test for PFAS

Standard home water test kits do not cover PFAS -- their molecular size and chemical properties require laboratory analysis rather than colorimetric strip testing. A water test kit from a certified laboratory that specifically includes PFAS panels is the appropriate starting point for households with known PFAS concerns. The EPA's PFAS-certified laboratory list and the EWG PFAS contamination map (available at ewg.org) provide geographic context for which areas have confirmed PFAS contamination in public supplies.

Which Filtration Methods Remove PFAS

Not all filtration methods address PFAS effectively. The table below summarizes what the research shows.

Reverse osmosis is the most thoroughly validated residential technology for PFAS removal across both long-chain and short-chain compounds. The RO membrane's sub-nanometer pore structure physically blocks PFAS molecules regardless of chain length. Systems certified under NSF/ANSI 58 with specific PFAS reduction claims have been independently verified.

High-contact-time activated carbon is the second most practical approach for residential point-of-entry treatment, with large-format GAC or carbon block systems showing meaningful PFAS reduction -- particularly for long-chain compounds like PFOA and PFOS.

The USWF PFAS 2-Stage Filtration System uses a 20-inch PFAS carbon block certified to NSF 53 for PFOA/PFOS reduction, capable of reducing up to 98% of PFOA/PFOS at the whole-house point of entry. It includes a Stage 1 sediment filter and a Stage 2 high-capacity 0.5-micron PFAS carbon block in a 20x20-inch Big Blue dual housing configuration.

For point-of-use drinking water with the most thorough PFAS reduction, the USWF 600GPD Tankless RO system removes PFAS as part of its broad dissolved contaminant reduction across the RO membrane. The DFS reverse osmosis buying guide covers system selection by household size and contaminant profile. The under-sink RO systems collection and the full RO filtration systems collection cover available systems across capacity levels.

For households that want the most comprehensive approach -- whole-house PFAS carbon block at the point of entry combined with RO at the kitchen tap -- this layered approach provides PFAS reduction at every faucet while delivering the most thoroughly treated water for drinking and cooking.

The best home water filtration systems guide covers how to layer whole-house and point-of-use treatment for households with multiple water quality concerns including PFAS.

Questions about which PFAS filtration solution fits your household? Call the DFS team at 1-800-277-3458.

Frequently Asked Questions

What are PFAS and why are they in drinking water?

PFAS (per- and polyfluoroalkyl substances) are thousands of synthetic chemical compounds used in industrial products including non-stick coatings, stain-resistant fabrics, food packaging, and firefighting foam.

They are called "forever chemicals" because the carbon-fluorine bond that defines them is one of the strongest in organic chemistry -- they do not break down naturally in the environment or in human tissue. They contaminate groundwater and surface water near industrial sites, military bases, and airports where firefighting foam was used.

What are the new EPA PFAS limits in drinking water?

In April 2024, the EPA finalized Maximum Contaminant Levels of 4 parts per trillion for PFOA and PFOS individually, and 10 parts per trillion for PFNA, PFHxS, and HFPO-DA (GenX) individually. A hazard index applies to mixtures of four shorter-chain PFAS. Public water utilities have until 2027 to comply. Private well owners are not covered by these regulations.

Does reverse osmosis remove PFAS?

Yes. Reverse osmosis is one of the most thoroughly validated residential technologies for PFAS removal, reducing both long-chain and short-chain PFAS by 90 to 99% or more across most compounds. The RO membrane's sub-nanometer pore structure physically blocks PFAS molecules regardless of chain length. Systems certified to NSF/ANSI 58 with specific PFAS reduction claims have been independently verified.

Does boiling water remove PFAS?

No -- boiling makes the problem worse. PFAS do not volatilize or decompose at normal boiling temperatures. As water evaporates during boiling, dissolved PFAS become more concentrated in the remaining liquid. Never boil water as a PFAS treatment.

Can a standard carbon pitcher filter remove PFAS?

Standard pitcher filters using granular activated carbon provide limited PFAS reduction, particularly for short-chain PFAS compounds. While high-contact-time GAC can reduce longer-chain PFAS compounds, pitcher filters have relatively short contact time and small carbon volumes. They are not the recommended approach for households with confirmed PFAS concerns. NSF 53 certified carbon block filters or RO systems are the more reliable choices.

Are private well users at risk from PFAS?

Yes, potentially. The 2024 EPA MCLs apply only to regulated public water systems, not private wells. Well owners in areas near industrial sites, military bases, or airports that used AFFF firefighting foam should test specifically for PFAS through a certified laboratory. The EWG PFAS contamination database provides geographic context for known contamination areas.

What is the difference between whole-house PFAS filtration and point-of-use RO for PFAS?

A whole-house PFAS carbon block system reduces PFAS at every tap, shower, and appliance in the home. A point-of-use RO system provides the most thorough PFAS reduction specifically at the kitchen drinking tap. For households with confirmed PFAS and concerns about bathing and cooking exposure as well as drinking water, combining both approaches provides the most comprehensive coverage. For households primarily concerned with drinking water, point-of-use RO alone is the most practical starting point.