In one of the most significant regulatory shifts of 2025, the U.S. Environmental Protection Agency announced a partial revision of the National Primary Drinking Water Regulation (NPDWR) for PFAS. While the agency confirmed it would retain the maximum contaminant levels (MCLs) for PFOA and PFOS at 4 parts per trillion (ppt) each, it simultaneously announced its intent to rescind the individual MCLs for perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and HFPO-DA (GenX), as well as the hazard index for their mixtures.
What Changed and What Stayed the Same
The April 2024 NPDWR established the first-ever legally enforceable MCLs for six PFAS compounds in U.S. public drinking water. Under the May 2025 announcement, PFOA and PFOS MCLs remain at 4 ppt—but the compliance deadline has been extended from 2029 to 2031, giving water utilities two additional years to implement treatment solutions. For PFHxS, PFNA, HFPO-DA (GenX), and their mixtures, EPA intends to publish a proposed rule in fall 2025 and finalize rescission in spring 2026.
State Regulations Fill the Federal Gap
As federal protections retreat for four PFAS compounds, states are moving in the opposite direction. Massachusetts enforces a 20 ppt combined MCL for six PFAS. Michigan mandates 8 ppt each for PFOA and PFOS. California has set 5 ppt each. These state-level standards remain in force regardless of federal rollbacks, sustaining commercial demand for multi-compound PFAS filtration systems capable of simultaneously addressing PFOA, PFOS, PFHxS, and PFNA.
Monitoring Requirements Remain Active
Even if MCLs for four compounds are rescinded, the monitoring program established under the 2024 NPDWR continues. All public water systems are required to complete initial PFAS monitoring by 2027. This data will drive state-level regulatory responses and generate sustained demand for point-of-use and municipal treatment systems.
Implications for OEM Filter Manufacturers
NSF/ANSI 53 and NSF/ANSI 58 certifications demonstrating PFOA and PFOS removal at or below 4 ppt remain the market baseline. State-level procurement specifications in Massachusetts, Vermont, and Michigan will continue requiring documented removal of PFHxS and PFNA. OEM suppliers should document multi-compound removal performance across the full suite of legacy and emerging PFAS to satisfy the growing diversity of state-level specifications.