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PFAS in Your Drinking Water: the 2024 EPA Limits, Explained

April 2024: EPA finalized the first enforceable drinking-water Maximum Contaminant Levels for six PFAS compounds. The action levels are the lowest in any contaminant rule's history — and the compliance window is short.

Published 2026-04-25 · Last reviewed 2026-07-03 · methodology

What PFAS is

Per- and polyfluoroalkyl substances (PFAS) are ~15,000 synthetic chemicals used since the 1940s in non-stick coatings, fire-fighting foam, water-repellent fabrics, food packaging.

Once in groundwater, PFAS persist for decades — hence 'forever chemicals'. Linked to thyroid disease, kidney cancer, immune-system suppression, and developmental effects.

About 45% of US tap water has detectable PFAS per a 2023 USGS sampling study.

The 2024 MCL rule

Six compounds regulated: PFOA, PFOS (each MCL 4.0 ppt), PFHxS, PFNA, GenX (each MCL 10.0 ppt), plus a Hazard Index for PFHxS+PFNA+GenX+PFBS mixtures.

PFOA + PFOS at 4 parts per trillion — that's roughly 4 drops in 20 Olympic swimming pools. The detection limit is ~2 ppt; many utilities will be required to install treatment because they can't meet 4 ppt without removal.

Compliance schedule: monitoring required by 2027; treatment in place by 2029. Some communities pushing back on cost; lawsuits filed by utility-trade associations.

Where PFAS shows up most

Near military bases (firefighting-foam runoff): especially around Air Force facilities + Navy training areas.

Near manufacturing facilities: 3M (Minnesota, Alabama, Belgium); DuPont/Chemours (West Virginia, North Carolina Cape Fear basin); Solvay (NJ).

Downstream of paper mills, textile plants, electroplating facilities — historically.

Cape Fear basin (Wilmington NC), Hoosick Falls (NY), Decatur (AL), and Parkersburg (WV) are documented hotspots.

Reading utility PFAS results

Pre-2024 testing was voluntary; many utilities have UCMR (Unregulated Contaminant Monitoring Rule) results from UCMR3 (2013-2015) and UCMR5 (2023-2025). Compare your utility's UCMR5 to the new MCLs.

If your utility shows PFOA above 4 ppt OR PFOS above 4 ppt → treatment is required by 2029. Most utilities will install granular activated carbon (GAC) filters or ion-exchange resin.

If you're on a private well + you live near a documented hotspot, get a PFAS test ($300-500 typical). Reverse-osmosis filtration handles PFAS.

What zipradar shows

EPA SDWIS data per utility — though PFAS-specific compliance data lags behind pre-2027 monitoring.

Where UCMR5 results are public, we'll surface them per ZIP starting Q3 2026.

We don't show speculative PFAS risk; we show measured violations. If a utility hasn't tested yet under the new rule, we say so explicitly.