PFAS in Well Water: Who Should Test, What the Numbers Mean, and What Works

Not every well needs a $250–$600 PFAS test, but wells near firefighting-foam sites, PFAS-using factories, landfills, or fields spread with sewage sludge do. Results come in parts per trillion: EPA's limit for PFOA and PFOS is 4.0 ppt each. Certified reverse osmosis, activated carbon, and PFAS-selective ion exchange remove them when maintained. EPA's rules skip private wells, so here's how to decide, cheapest step first.

Does your well need a PFAS test?

Test if your well is near a likely PFAS source, a state investigation or advisory covers your area, or you're buying a home there. Far from any source, it's a lower priority — Minnesota's health department, for one, doesn't recommend PFAS testing for every private well.

• Firefighting foam: airports, military bases, and fire-training areas; nearness to fire-training areas was a top PFAS predictor in USGS sampling.
• Industry and landfills: chemical, plastics, and textile plants that made or used PFAS, plus active or closed landfills.
• Sewage sludge on fields: Maine banned spreading it on farmland in 2022 and has been testing private wells near former sludge and septage spreading sites.
• Septic systems: household wastewater carries PFAS from everyday products, and a 2024 USGS-led study linked heavier septic loading to higher PFAS odds — another reason to mind what goes down the drain.

USGS found at least one PFAS in 20% of the eastern U.S. domestic wells it sampled in 2019, and its national model finds shallow wells in developed areas more likely to have PFAS, so know your well's depth. Buying a house with a well near any of these sources? Add PFAS to the purchase test. New Jersey has required PFOA, PFOS, and PFNA tests in sales of homes with wells since December 2021.

How do you test well water for PFAS?

Order a kit from a state-certified or accredited lab that runs EPA Method 533 or 537.1, and follow its instructions exactly. Expect roughly $250–$600 per sample and two to four weeks for results. Call your state health department first: some states test wells near known contamination for free.

Everyday materials can taint a sample, so New Jersey's instructions say:

• Use only the lab's bottles; they're pre-cleaned and hold a preservative.
• On sampling day, skip waterproof, stain-resistant, or fabric-softened clothing, plus sunscreen, insect repellent, moisturizers, and cosmetics.
• Keep food wrappers, foil, and sticky notes away; pull the aerator; avoid Teflon thread tape; run the water several minutes first.

PFAS isn't in standard panels, so add it to your routine well tests, and ask if the lab bills a "field blank" as a second sample.

What do the PFAS numbers on your report mean?

Results are listed in ng/L, which equals parts per trillion — a thousand times smaller than the parts per billion used for lead or arsenic. Compare PFOA and PFOS with EPA's 4.0 ppt limit, and treat any result above it as a reason to act.

• PFOA and PFOS: 4.0 ppt each; EPA's health goal is zero, and the limit is as close as EPA judged feasible.
• PFHxS, PFNA, and HFPO-DA (GenX): 10 ppt each under the 2024 rule.
• Hazard index for mixtures: divide PFHxS, PFNA, and GenX by 10 and PFBS by 2,000, then add. The limit is a hazard index of 1, and because public systems round to one digit, a violation starts at 1.5. So 8 ppt PFHxS plus 7 ppt PFNA (0.8 + 0.7 = 1.5) fails though each is under 10.
• "ND": not detected. Reports often list 18 to 29 PFAS, and most have no federal limit.
• State yardsticks: New Jersey caps PFOA, PFOS, and PFNA at 13–14 ppt; New York applies its 10 ppt PFOA and PFOS standards to private wells as guidelines.

Where do federal PFAS limits stand in 2026?

Only the PFOA and PFOS limits still have EPA's backing: 4.0 ppt each, with public systems due to comply by April 2029, or 2031 for systems granted extra time if a pending proposal becomes final. EPA has proposed rescinding the other four standards, and a lawsuit by water utilities and industry groups is unresolved. None of it covers private wells.

• April 2024: EPA finalized the rule (published April 26): the six standards above, with compliance due in 2029.
• May 14, 2025: EPA said it would keep the PFOA and PFOS limits, seek a 2031 deadline, and rescind and reconsider the other four.
• January and March 2026: the D.C. Circuit (American Water Works Association v. EPA) refused EPA's requests to vacate those four standards summarily or split them off and pause; they stay on the books for now.
• May 18, 2026: EPA proposed two rules (published May 20): optional extensions to April 2031 for eligible systems that ask, with the 4.0 ppt limits unchanged, and rescission of the other four. Comments closed July 20.
• As of September 17, 2026: neither proposal is final, and the case is still pending.

Can you shower, cook with, or boil water that has PFAS?

Showering and bathing are fine; EPA and ATSDR say little PFAS passes through skin. If levels are elevated, use certified-treated water or bottled water the bottler says is tested for PFAS for drinking, cooking, brushing teeth, and mixing infant formula. Don't boil it: boiling leaves the PFAS behind in less water.

EPA and ATSDR link long-term exposure to certain PFAS with higher cholesterol, lower antibody response to some vaccines, small decreases in birth weight and other developmental effects, hormone interference, and higher risk of some cancers, including kidney and testicular. Risk depends on dose and duration, and a result over a limit doesn't necessarily mean anyone will get sick. Keep breastfeeding; ATSDR says the benefits outweigh the potential PFAS risk.

Which home treatment removes PFAS?

Three kinds work: reverse osmosis, activated carbon, and PFAS-selective ion exchange. A kitchen-tap unit certified to NSF/ANSI 58 (RO) or 53 (carbon) for PFOA/PFOS reduction covers drinking water; whole-house carbon or resin covers every tap. Softeners, sediment filters, and iron filters don't remove PFAS.

RO also cuts nitrate, arsenic, and lead, making it the usual kitchen-tap pick on a well; on septic, Massachusetts regulators favor two-stage under-sink carbon. See our treatment cost guide for where each fits.

How do you know the treatment is still working?

Test the treated water about a week after installation, then roughly every six months. On a two-tank whole-house system, sample the port between the tanks: once PFAS shows up there, the second tank moves up front and a fresh one goes in behind it.

• Tank life: at low to moderate levels, the lead tank can last two-plus years, Massachusetts regulators say.
• Routine parts: replace the sediment prefilter at least yearly ($10–$20) and any UV bulb and sleeve yearly ($150–$250).
• Shock chlorination: before you shock the well, ask about bypassing the carbon; Minnesota regulators note that chlorine can quickly use up its capacity.

Ask about help first. New York's 2026 pilot tests eligible wells in six counties for free and offers rebates of up to $5,000 for treatment when PFOA or PFOS is 10 ppt or higher. New Hampshire's rebate of up to $5,000 covered systems installed by September 30, 2026; check whether it has been extended. A known polluter may have to pay: a 2019 North Carolina consent order makes Chemours supply clean water to qualifying wells near its plant.