November 5, 2025

How Water Systems Can Navigate the Uncertain PFAS Regulatory Landscape

David Jackson

Water and Wastewater Treatment Practice Leader

Viraj deSilva

Senior Treatment Process Engineer

Ongoing litigation and the U.S. federal government shutdown that started in October have added more uncertainty to how water systems should proceed with their planning for meeting restrictions on PFAS in drinking water.

As communities and water utilities plan their compliance programs, they should operate based on the best available information. While the landscape could continue to shift, these details can provide guidance:

What will be regulated?

In 2024, the Environmental Protection Agency set strict limits on six types of per- and polyfluoroalkyl substances under the Safe Drinking Water Act to reduce the risks of health impacts from PFAS. However, in May of 2025, the EPA said it planned to scale back that rule.

In September, the agency told a federal appeals court that it intends to enforce a limit of 4.0 parts per trillion (ppt) 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).

The EPA asked the court to strike down the limits on the other four PFAS substances, saying those restrictions had been adopted without following proper procedures. The appeals court is considering a lawsuit by the American Water Works Association and the Association of Metropolitan Water Agencies. The AWWA and AMWA support striking down the four limits the EPA wants to drop, but want the agency to go further. The groups support PFAS restrictions to protect public health but have taken issue with the 4.0 ppt limit on PFOA and PFOS, saying it imposes significant nationwide costs without resulting in safer drinking water.

The Natural Resources Defense Council, meanwhile, argues in a separate federal court case that because of the chemicals’ health risks, EPA should regulate PFAS even more strictly rather than “backsliding” on the rules.

What’s the compliance deadline?

The EPA announced in May 2025 that it plans to delay the compliance deadline to 2031 (instead of 2029), which provides more time for planning and implementing treatment solutions. However, any changes at this point must go through the federal rulemaking process.

In the spring, the agency said it expected to issue a proposed rule in fall 2025, open it for a 60-day public comment period and finalize the rule in spring 2026. The court challenge by the water groups is likely to unfold on the same timeline, though activity in the case was paused during the government shutdown. To date, EPA has not confirmed the revised compliance timeline.

How can water utilities proceed?

Continuing to plan and execute early steps in your compliance plan will prepare you as the rule changes develop. Flexibility is also important because of the simultaneous rulemaking and court processes. Regardless of the EPA’s recent request to repeal part of the 2024 rule, it remains intact with a 2029 deadline and will continue to be enforceable until any modifications are officially adopted.

These steps also offer guidance:

Review and adjust your capital spending plans for PFAS testing, monitoring and treatment upgrades.
Finish occurrence monitoring, conduct pilot testing to identify optimal PFOA/PFOS treatment, and line up state or federal funding that’s still available.
Keep track of your state’s PFAS regulations; if they’re stricter than the federal rules, they will apply regardless of EPA changes.
Consult EPA tools, such as the PFAS OUT (Outreach, Understanding and Training) targeted outreach program and WaterTA, the Enhanced Water Technical Assistance program, which provides free services (including water quality testing, treatment planning, operator training and funding support) to help systems meet PFAS standards.
As PFAS regulations continue to evolve, effective communication with customers and community partners is just as important as technical compliance.