USEPA to Retain National Primary Drinking Water Regulation for PFOA and PFOS with a Delayed Compliance Date, Amend Regulation for Other PFAS
On May 14, 2025, the United States Environmental Protection Agency (USEPA) announced its intention to amend the National Primary Drink Water Regulation (NPDWR) for six PFAS:
- Perfluorooctanoic acid (PFOA)
- Perfluorooctane sulfonic acid (PFOS)
- Perfluorohexane sulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX chemicals)
- Perfluorobutane sulfonic acid (PFBS)
Current PFAS MCLs and Health-Based Water Concentrations
The NPDWR established MCLs, which are enforceable drinking water standards that consider available treatment technologies and costs. In April 2024, individual MCL values were finalized for five PFAS and a Hazard Index MCL was finalized for four PFAS. Health-based water concentrations, which are used to calculate the Hazard Index, were also established for four PFAS. MCLs and health-based water concentrations are summarized in the table below.
Delayed Compliance of PFOA and PFOS Regulations
In its announcement, USEPA indicated that it will keep the NPDWR for PFOA and PFOS. However, to “allow drinking water systems more time to develop plans for addressing PFOA and PFOS where they are found and implement solutions,” USPEA plans to develop rulemaking to extend the NPDWR compliance date by two years from 2029 to 2031. USEPA plans to issue a proposed rule this fall and finalize this rule the following spring. Additionally, USEPA announced it will support the United States Department of Justice in defending ongoing legal challenges to the PFAS NPDWR as it relates to PFOA and PFOS.
Rescindment of PFHxS, PFNA, HFPO-DA, and PFBS Regulations
USEPA indicated that it intends to “rescind the regulations and reconsider the regulatory determinations for PFHxS, PFNA, HFPO-DA (commonly known as GenX), and the Hazard Index mixture of these three plus PFBS to ensure that the determinations and any resulting drinking water regulation follow the legal process laid out in the Safe Drinking Water Act.” USEPA did not provide additional information such as the timing of this planned action.
Additional Actions
USEPA also announced that it will launch a new PFAS OUTreach Initiative (PFAS OUT) to “connect with every public water utility known to need capital improvements to address PFAS in their systems, including those USEPA has identified as having PFOA and PFOS levels above USEPA’s MCL. EPA will share resources, tools, funding, and technical assistance to help utilities meet the federal drinking water standards.” PFAS OUT will be in addition to Water Technical Assistance (WaterTA) that provides water systems with free services such as water quality testing, development of technical plans, operator training support, designing public engagement and outreach strategies, and support for accessing federal funding opportunities
Questions?
If you have any questions or would like to discuss how PFAS may impact your business, please email pfas@geosyntec.com to be connected with one of our PFAS technical experts.
