Federal PFAS Regulatory Changes: What Water Systems Should Know — And Do

David Jackson

Water and Wastewater Treatment Practice Leader

Viraj deSilva

Senior Treatment Process Engineer

The Environmental Protection Agency is shifting some aspects of its approach to regulating PFAS in drinking water, including extending the timeline for complying with the limits.

Because of these changes, water utilities should assess what adjustments are appropriate for their compliance programs. Strict limits for per- and polyfluoroalkyl substances under the Safe Drinking Water Act were announced in 2024 to reduce the risks of health impacts from PFAS. The agency said in its new announcement on May 14 that it aims to make compliance achievable and hold polluters responsible.

Here are answers to key questions:

How will the limits change?

• 4.0 parts per trillion (ppt) will remain the limit for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), two types of PFAS commonly found in drinking water. These are called Maximum Contaminant Levels (MCLs).
• Four previous limits are being dropped and reconsidered: 10.0 parts per trillion for perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX), and perfluorohexane sulfonic acid (PFHxS), and a Hazard Index rule applying to any combination of two or more PFHxS, PFNA, GenX and a fourth substance, PFBS.

How will the compliance deadline change?

EPA has proposed extending the compliance deadline to 2031 (instead of 2029) for water systems that exceed one or more of the limits (MCLs) to reduce them and notify the public about the violation.

When will the changes take effect?

The changes must go through the federal rulemaking process. EPA plans to issue the proposed rule in fall 2025, open it for a 60-day public comment period, and finalize the rule in spring 2026. The proposed rule could undergo revisions until finalized.

What steps should water utilities take?

• Review and adjust your capital spending plans for PFAS testing, monitoring and treatment upgrades.
• Use the extra two years wisely: Finish occurrence monitoring, pilot‑scale the simplest PFOA/PFOS treatment, and line up state or federal funding while it’s still earmarked. Additional federal funding is unlikely under the Bipartisan Infrastructure Law, though support might be available for disadvantaged communities.
• Stay flexible because litigation over the scope and timing of the regulations will continue even as the rulemaking process goes forward. These newly announced changes might not be the last that can be expected.
• Keep track of your state’s PFAS regulations; if they’re stricter than the federal rules, they apply regardless of changes made through EPA.

What else should water utilities know?

PFAS OUT: EPA plans a targeted outreach program to help water systems, especially small and rural, by sharing resources, tools, funding and technical assistance.

WaterTA: The Enhanced Water Technical Assistance program will continue, providing free services (water quality testing, treatment planning, operator training, funding support) to help systems meet PFAS standards.

How Freese and Nichols Can Help

With our team’s expertise and experience in environmental science and water treatment, we can assist you with all aspects of PFAS regulatory compliance.

To learn more, contact David Jackson, david.jackson@freese.com, or Viraj deSilva, viraj.desilva@freese.com

David Jackson, PE, BCEE, is Water and Wastewater Treatment Practice Leader, based in Fort Worth.

Viraj deSilva, PhD, PE, BCEE, is a Senior Treatment Process Engineer and national PFAS expert based in Tampa, Florida.