PFAS (Forever Chemicals)

Synthetic compounds that don't biodegrade — the EPA acknowledged in 2024 that there's no safe level

EPA MCL

PFOA & PFOS: 4 ppt (parts per trillion); PFHxS, PFNA, GenX: 10 ppt (2024 MCLs)

Health concern

Kidney and testicular cancer; immune dysfunction; developmental effects; cholesterol elevation; thyroid effects

Testing method

EPA Method 537.1 or 533 by certified lab; $250-450; not on standard well panels

PFAS — per- and polyfluoroalkyl substances — are the synthetic chemicals at the center of the slowest-moving environmental crisis in the United States. They were invented in the 1940s for non-stick coatings (Teflon) and waterproofing. They became widespread in firefighting foam used at military bases and airports, in food packaging, in water-resistant clothing, in carpets, in semiconductor manufacturing. Their carbon-fluorine bond is among the strongest in nature; it does not biodegrade. Once PFAS are in groundwater, they stay there indefinitely on any human timescale. There is no natural process that removes them.

The colloquial name is right: forever chemicals. The EPA admitted in its 2024 final rule that the lifetime Health Advisory Level for PFOA — the most-studied PFAS — is 0.004 parts per trillion. That number is functionally zero; it's below what most labs can reliably measure. The EPA's enforceable MCL of 4 ppt is what's actually testable, and it is still the strictest drinking-water standard the agency has ever set.

The scale of the problem

USGS modeling published in 2023 estimated that at least 200 million Americans are exposed to PFAS in drinking water. The 2024 EPA MCLs, when fully implemented (compliance deadline 2029), will require water utilities serving roughly 100 million people to install PFAS treatment they don't currently have.

For private well owners, the situation is worse: your well is not regulated. The EPA MCL applies to public water systems. If you're on a private well, nobody is testing your water for PFAS unless you pay for it yourself, and standard well-water test panels do not include PFAS.

Where it shows up

PFAS contamination is overwhelmingly attributable to specific point sources, not diffuse environmental pollution. The major categories:

• Military bases — AFFF (aqueous film-forming foam) was the standard firefighting foam for jet fuel fires from the 1970s to the early 2020s. Routine training drills released enormous quantities into base groundwater. The DoD has identified over 700 contaminated military sites; cleanup is decades away. Wells within several miles downgradient of any current or former military airfield should be tested.
• Civilian airports — same AFFF story, somewhat smaller scale.
• Chemical manufacturing legacy sites — DuPont's Parkersburg WV operation, 3M's Cottage Grove MN site, Saint-Gobain's Hoosick Falls NY plant. Plumes extend miles.
• Wastewater-impacted areas — PFAS concentrate in biosolids that get land-applied as fertilizer; some Maine farms have been condemned because PFAS in the soil now contaminates the well water.
• Industrial corridors — semiconductor fabs, electroplating operations, paper mills with grease-resistant packaging lines.

If your well is in any of these categories of geography — within a few miles of a military airfield, downstream of a known industrial site, in a state with known biosolid land-application — you should test for PFAS. The EPA's EJScreen and the Environmental Working Group's PFAS contamination map are useful starting points to identify whether your area is suspect.

Health effects

The 2022 National Academies report and the EPA's 2024 final rule documents are the current canonical references. The strongest evidence supports:

• Kidney cancer — strong epidemiological evidence (PFOA)
• Testicular cancer — strong evidence (PFOA)
• Immune dysfunction — reduced antibody response to childhood vaccines; this is the endpoint that drove the most aggressive 2024 standards
• Developmental effects — low birth weight, delayed development
• Cholesterol elevation — consistent across studies
• Thyroid effects — moderate evidence
• Possible: liver effects, ulcerative colitis, pre-eclampsia

PFAS bioaccumulate. The half-life of PFOA in human serum is several years. Once you've been exposed, your body burden persists long after the exposure ends.

Testing

PFAS testing is not on standard well-water panels. You have to ask for it specifically and pay separately:

• Method: EPA Method 537.1 or 533 by a certified lab. Mass-spec methods that detect dozens of PFAS compounds.
• Cost: $250-450 per sample. Significantly more than basic panels because of the analytical complexity.
• What to test: at minimum the six EPA-regulated compounds (PFOA, PFOS, PFHxS, PFNA, HFPO-DA aka GenX, and PFBS). Many labs offer 18-40 compound panels for similar cost — worth taking.
• Sampling: PFAS contaminate easily. Don't use soap with PTFE coatings on hands before sampling, don't use pre-treated containers, follow the lab's instructions exactly.

Treatment

Standard pitcher filters (Brita, PUR) and standard refrigerator filters do not remove PFAS reliably. Most carbon block filters certified for PFAS reduction are NSF/ANSI Standard 53 certified — check the certification before trusting any product.

What works:

• Granular activated carbon (GAC) — works for long-chain PFAS (PFOA, PFOS) effectively. Less effective for short-chain (PFBS, GenX). Whole-house POE systems are common; need replacement based on water volume, not time.
• Anion exchange (PFAS-specific resins) — newer, generally outperforms GAC for the difficult short-chain compounds. More expensive media but better single-pass removal.
• Reverse osmosis — removes virtually all PFAS reliably. Best at point-of-use (kitchen tap). Whole-house RO is expensive and high-waste.

For a contaminated well, the standard residential answer is: GAC or anion-exchange whole-house POE for everything, plus RO at the kitchen tap for drinking and cooking water. Cost: $1,500-4,000 installed plus ongoing media replacement.

Aquifers where this is a concern