Ten pillar guides on PFAS in US drinking water. Each one cites every numeric threshold back to a federal rule, peer-reviewed paper, or NSF standard. Read these to understand what's behind the $15 brief, or to do the lookup yourself.
The first federally-enforceable PFAS MCLs: 4.0 ng/L for PFOA + PFOS, 10 ng/L for PFHxS/PFNA/HFPO-DA, plus a Hazard Index. Compliance by 2029.
EPA's UCMR 5 (2023–2025) is the largest PFAS dataset ever collected. How to find your utility on NCOD and what the numbers mean.
What ATSDR's 2021 profile, IARC Monograph 110 + 135, and the C8 Science Panel actually concluded about PFOA and PFOS in humans.
NSF 42, 53, 53 P473, 58, 401, what each certification actually proves about PFAS removal. The P473 protocol is the one to look for.
The Duke University 2020 study: under-sink RO removes >94% of PFAS; most pitcher filters remove 0–30%. The data, by filter type.
USGS, EWG, and state-DEP data point to the same hotspots: AFFF firefighting-foam sites, Chemours Fayetteville, 3M Decatur, military bases.
The 2005 DuPont settlement created a 7-year independent science panel. It found "probable links" to six diseases. The data that built the 2024 MCL.
EFSA's 2020 Tolerable Weekly Intake is 4.4 ng/kg body weight per week for the sum of four PFAS. What that means in pregnancy.
Three credible mail-in PFAS tests for tap water. EPA Method 537.1, NELAP accreditation, kit prices, sample-collection protocol.
Michigan, New Jersey, New Hampshire set enforceable state PFAS MCLs years before the EPA. Per-compound thresholds, by state.
