Water utilities continue to grapple with uncertainty as they evaluate compliance obligations arising out of the first-ever National Primary Drinking Water Regulation (NPDWR) for per- and polyfluoroalkyl substances (PFAS), issued by the Biden EPA in April 2024. That rule established enforceable drinking water standards known as maximum contaminant levels (MCLs) for five individual PFAS chemicals (PFOA, PFOS, PFNA, PFHxS, and HFPO-DA (GenX)), as well as a hazard index-based MCL for mixtures of two or more of PFNA, FHxS, GenX, and PFBS. The regulation requires public water systems to complete initial monitoring (based on quarterly or twice-yearly samples, depending on the size and type of system) by April 2027, to implement controls to achieve the MCLs by April 2029, and thereafter to provide public notification to consumers if MCLs are violated. Several water groups challenged the April 2024 rule; litigation is underway in the United States Court of Appeals for the District of Columbia Circuit.
Following President Trump's inauguration, the litigation was held in abeyance for several months as EPA evaluated its position. Last May, EPA announced its intention to defend the MCLs for PFOA and PFOS and at the same time stated it would take regulatory action to ease the compliance deadlines for these two chemicals. Specifically, EPA said it would "develop a rulemaking to provide additional time for compliance, including a proposal to extend the compliance date [from 2029] to 2031." EPA's statement indicated that a proposal would be issued in the fall of 2025, with a final rule slated for spring of 2026. As of the writing of this update, however, EPA has taken no such regulatory action; to date, no proposal to revise the compliance timeframe appears to have been submitted to the Office of Information and Regulatory Affairs (OIRA) for EO 12866 regulatory review.
In the same May 2025 statement, EPA suggested that the MCLs and underlying regulatory determinations for the other four PFAS chemicals addressed in the 2024 rule (PFNA, PFHxS, GenX, and PFBS) may not have followed "the legal process laid out in the [SDWA]," and announced that the Agency intended to rescind those regulations and reconsider the underlying regulatory determinations for those chemicals. Then, in September 2025, EPA moved for vacatur of the MCLs and underlying regulatory determinations for those four chemicals in the ongoing litigation in the D.C. Circuit. In its motion, EPA argued that the Agency lacked the statutory authority to propose an NPDWR simultaneously with a preliminary regulatory determination for a contaminant; EPA pointed out that "in the absence of vacatur, obligated parties could eventually be forced to comply with regulations that may ultimately change and are, in EPA's view, unlawful under the statute."
Certain industry stakeholders were optimistic that vacatur by the court would prove the smoothest path to removing those requirements, as some argue that the legal path to rescind them under SDWA is murky. However, on January 21, the D.C. Circuit denied EPA's motion for vacatur of the MCLs and underlying regulatory determinations for PFNA, PFHxS, GenX, and PFBS.
Practical Considerations: Looming Compliance Obligations Against the Backdrop of Anticipated Regulatory Changes
For parties evaluating compliance obligations under the NPDWR, the original regulatory requirements remain on the books. The existing regulations require public water systems to complete initial monitoring by April 2027, meaning regulated entities will soon have to gear up to begin sampling. The requirements to implement controls to meet the MCLs (i.e., for the five individual PFAS and, under the hazard index approach, for mixtures of PFNA, PFHxS, GenX, and PFBS) and to notify the public regarding violation of the MCLs kick in in 2029. These regulatory obligations remain in place despite EPA's stated plans to ease the compliance schedule for PFOA and PFOS and to rescind the regulations for the other four PFAS chemicals.
Navigating PFAS Regulatory and Liability Considerations
Venable attorneys across the Environmental, Government Affairs, Products Liability, Food and Drug, Insurance, and Commercial Litigation groups are working together to track the regulatory, legislative, and litigation developments evolving nationwide that involve PFAS. Together, we can assist companies in identifying regulatory obligations and developing and implementing compliance strategies, assessing and mitigating exposure and risk, and pursuing advocacy as EPA and other federal and state agencies pursue PFAS-related rulemakings and policies.