PFAS (Forever Chemicals)
A class of ~15,000 synthetic chemicals that don't break down. Now regulated for the first time.
The science, plainly.
PFAS — per- and polyfluoroalkyl substances — are a family of about 15,000 synthetic chemicals used since the 1940s in non-stick coatings, waterproof fabrics, firefighting foam, food packaging, and hundreds of other products. The carbon-fluorine bond at their core is one of the strongest in chemistry, which is why they are called 'forever chemicals' — they do not meaningfully break down in nature, in water-treatment plants, or in the human body.
The pathways into the tap.
- Firefighting foam used at military bases and airports
- Industrial discharge from manufacturers
- Landfill leachate
- Biosolids spread as agricultural fertilizer
- Atmospheric deposition (literally raining out of the sky)
What the evidence shows.
PFAS exposure is associated with kidney and testicular cancer, immune system suppression (including reduced vaccine response in children), thyroid disease, increased cholesterol, pregnancy-induced hypertension, and developmental effects in infants. The science is most certain on PFOA and PFOS — older, longer-chain compounds — but the newer 'replacement' PFAS like GenX show similar toxicity in animal studies.
Cancer
PFOA is classified by IARC as 'carcinogenic to humans' (Group 1) and PFOS as 'possibly carcinogenic' (Group 2B). The strongest associations are with kidney and testicular cancer.
Immune system
Even low-dose PFAS exposure reduces antibody response to childhood vaccines, suggesting immune suppression.
Pregnancy & infants
Linked to reduced fetal growth, low birth weight, and pregnancy-induced hypertension.
What the law allows vs. what's actually safe.
EWG recommends a 1 ppt combined limit — four times stricter than EPA.
Note: EPA also set MCLs for PFHxS, HFPO-DA (GenX), and PFNA, plus a Hazard Index for mixtures. Utilities have until 2029 to comply.
Where exposure is highest.
Detected in the tap water of at least 45% of U.S. samples (USGS, 2023). Highest concentrations near military bases, airports, and manufacturing sites — especially in the Mid-Atlantic, Great Lakes, and Southeast.
Filtration that actually works.
- Reverse osmosis (NSF/ANSI 58)
- Granular activated carbon (NSF/ANSI 53 + P473)
- Ion exchange resins
We don't recommend brands. The certification on the box matters more than the brand printed on it. Look for the actual NSF/ANSI standard number specific to the contaminant you're removing.
Sources
- PFAS National Primary Drinking Water Regulation (Final Rule, April 2024) — U.S. Environmental Protection Agency
- Toxicological Profile for Perfluoroalkyls — Agency for Toxic Substances and Disease Registry
- Perfluorinated Chemicals (PFAS) — National Institute of Environmental Health Sciences
- PFAS in US Tapwater (2023) — U.S. Geological Survey
- PFAS Contamination in the U.S. — Environmental Working Group