The PFAS MCL one year later: where the treatment buildout is actually happening

The federal PFAS maximum contaminant level (MCL) finalized in 2024 is, technically, a uniform compliance requirement on every public water system in the U.S. The reality on the ground in mid-2026 is that the treatment buildout is concentrating at a small set of utilities. The concentration is not random; it tracks two variables.

First, source-water PFAS exposure varies materially across U.S. utilities. The Great Lakes cohort, the Ohio River cohort, the Cape Fear River cohort, and the Pacific Northwest cohort carry materially higher source-water exposure than the average U.S. system. Second, the financial profile to fund the treatment buildout (GAC, IX, or membrane) varies even more materially. The intersection of high source-water exposure and investment-grade financial capacity is where the treatment buildout is concentrating.

The reference utilities

Greater Cincinnati Water Works is the operational reference for PFAS treatment at scale. The Richard Miller Treatment Plant has run granular activated carbon (GAC) at full scale since 2007 — seventeen years before the federal MCL was finalized. GCWW has expanded the system three times since then. The latest expansion landed in August 2025. Cincinnati is not in distress; Cincinnati is the textbook reference. Any contractor or chemical supplier pitching PFAS-treatment buildout elsewhere will cite GCWW.

The MWRA Carroll Water Treatment Plant in eastern Massachusetts is the New England regional reference. The 2025 expansion brought ozone-UV-GAC capacity in line with the more aggressive MA MCL framework. The procurement template at Carroll is the template that ripples out to the 61 MWRA member retail communities.

The LADWP San Fernando Basin program is the largest single PFAS-treatment-buildout opportunity in the West. Preliminary GAC and IX treatment cost is estimated at $740M. Cleveland's Garrett A. Morgan WTP intake, Pittsburgh's Aspinwall WTP, Toledo's Collins Park WTP, and Buffalo's WCWA collectively carry parallel Great Lakes source-water exposure.

The PFAS treatment buildout is not uniform. It is concentrating at the intersection of high source-water exposure and investment-grade financial capacity.

The actionable read

• The procurement-intensity cohort for PFAS treatment is small (under 50 utilities nationally) and structurally identifiable.
• Contractor and chemical-supply opportunities concentrate at the reference utilities; the marginal utility will copy the reference utility procurement template.
• Investment-grade credit rating plus high source-water PFAS exposure is the screen that filters the procurement-active cohort.
• The cohort outside this intersection (high exposure, low financial capacity) will use SRF principal forgiveness and federal grant programs; the procurement window is delayed, not skipped.

Read the curated cohort through this lens and the picture clarifies. The PFAS component of the composite score weights source-water exposure; the financial component weights credit rating; the intersection is visible on the cross-pillar quadrant. Contractors and suppliers concentrating attention at the intersection are pursuing the most procurement-stable subset of the PFAS treatment buildout.