U.S. EPA Outlines Next Steps to Vacate, Reconsider PFAS Drinking Water Rules 

The U.S. Environmental Protection Agency (EPA) is taking legal steps to address how it regulates certain per- and polyfluoroalkyl substances (PFAS). The action, initially announced on September 17, 2025, came after the agency asked the U.S. Court of Appeals for the D.C. Circuit on September 11, 2025, to partially vacate its 2024 drinking water PFAS maximum contaminant levels (MCLs) set by the rule for perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA), as well as for mixtures of these substances with perfluorobutane sulfonic acid (PFBS).

According to the EPA, the agency under the Biden administration used the wrong sequence to create the MCLs for PFAS under the Safe Drinking Water Act. The agency argues the statute requires a preliminary regulatory determination followed by a comment period before a final determination is made and a regulation is proposed. Claiming it proposed and finalized the PFAS rules at the same time it proposed the standards, the EPA, under Administrator Lee Zeldin, is now urging a federal court to strike down the PFAS regulations on these procedural grounds.

In a statement to 3E, the EPA explained its position, stating, “[The agency] is committed to protecting public health by addressing PFAS in drinking water while following the law and ensuring that regulatory compliance is achievable for drinking water systems.”

The EPA added that its court filing represents its intent to defend the drinking water regulations for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), which the agency says were developed according to the statute's proper sequence.

If the court vacates the rules, the EPA told 3E it would move forward with a proposed rulemaking to reconsider the regulations. While the agency said it cannot predetermine the outcome of this effort, it noted that the action “could result in a different outcome, including the potential for more stringent drinking water regulations for these PFAS in the future.”

Industry Celebrates, Advocacy Groups Worry

The EPA’s request to rescind the PFAS MCLs was met with mixed reactions. For environmental advocacy groups, this decision by the EPA marks a major step backward in regulating PFAS in the U.S. These groups argue that exposure to PFAS in drinking water may cause severe health effects, with some studies suggesting a link between PFAS exposure and increased risks of certain cancers, immune system changes, and developmental delays in children.

Betsy Southerland, a 30-year EPA veteran who retired in 2017 after directing the Office of Science and Technology in the Office of Water, strongly rejects the agency’s procedural defense. She told 3E that this is a technicality being used to dismantle “hard-won” protections.

“The Safe Drinking Water Act does not require those steps to be sequential, only that the agency provide public notice and comment, a process the EPA fully carried out,” Southerland explained.

Southerland also pointed out that the rollback could violate the “anti-backsliding” provision of the act, which prohibits rescinding finalized standards unless scientifically justified. Specifically, 42 U.S. Code § 300g-1 states, “Any revision of a national primary drinking water regulation shall be promulgated in accordance with this section, except that each revision shall maintain, or provide for greater, protection of the health of persons.”

“If Zeldin had simply proposed to rescind these rules without being sued, he wouldn't have been allowed to do it,” she said, describing the rollback effort as “absolutely heartbreaking.”

The legal challenge was also condemned by environmental groups like the Natural Resources Defense Council (NRDC).

“The EPA's request to jettison rules intended to keep drinking water safe from toxic PFAS forever chemicals is an attempted end-run around the protections that Congress placed in the Safe Drinking Water Act (SDWA),” said NRDC Senior Attorney Jared Thompson in a statement. “It is also alarming, given what we know about the health harms caused by exposure to these chemicals … We will continue to defend these commonsense, lawfully enacted standards in court.”

Industry groups, on the other hand, argue that by going through the courts, the EPA is upholding the law and fixing its original mistake in setting the MCLs without following the procedure laid out by the SDWA. In their original lawsuit, the water utilities, led by the Association of Metropolitan Water Agencies (AMWA) and the American Water Works Association (AWWA), argued that the EPA needs to follow the letter and the spirit of the SDWA and revisit deficient parts of the regulation.

“EPA's decision to ask the court to vacate the regulatory determinations for the Hazard Index PFAS is a positive step forward for the PFAS rule and the future of drinking water regulation,” said the AMWA. “If accepted by the court, EPA's request will reopen the opportunity for meaningful public input and ultimately lead to a more scientifically defensible final rule. It will also ensure that future rulemakings better respect the SDWA process, helping EPA, water utilities, and other partners identify risks and prioritize investments.”

The EPA's original rule, finalized in 2024, was grounded in extensive cost-benefit analysis, which concluded that the health and economic benefits of PFAS treatment far outweighed compliance costs. Southerland argues that because of this analysis, there is no justification for rescinding it, except to avoid making polluters spend money. She warns that if federal protections are rolled back, low-income and rural communities will bear the heaviest burden.

“Unless people want to spend their own money on filters for every faucet, and then constantly maintain them, they're just going to have to keep drinking PFAS,” Southerland said.

What Comes Next?

While the EPA awaits a decision from the court, the agency told 3E it will continue with two proposed rulemakings: one to extend the compliance deadlines for PFOA and PFOS and another to reconsider the regulations for the other substances. In a separate but related effort to establish a more consistent regulatory approach, the agency also plans to develop a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section 102(a) framework rule. This rule will provide a uniform approach for designating future hazardous substances and will outline how the EPA will consider the costs of a proposed designation, utilizing its authority under Section 102(a) to list new substances not already covered by other federal laws.

Terry Wells, associate director of regulatory research at 3E, provided her perspective on the regulatory challenges, specifically those related to CERCLA.

“PFAS contamination presents one of the most complex environmental and regulatory challenges of our time,” Wells said. “Given the scope of potential liabilities under CERCLA and the costs to both industry and communities, it is important that EPA's regulatory framework provides both clarity and consistency while continuing to protect public health and the environment.”

Wells also noted that the progress made to date in addressing PFAS should not be “set aside.”

“A balanced approach that builds on the work already accomplished, while refining the framework to address legitimate concerns, will best serve the long-term public interest,” Wells added.

To help communities prepare, the EPA has launched a new PFAS OUTreach Initiative (called PFAS OUT) to connect with every public water system known to need system upgrades to address PFAS. The agency also highlighted existing funding opportunities, including the State Revolving Fund (SRF) and the Water Infrastructure Finance and Innovation Act (WIFIA) loan program, which offer low-interest loans for PFAS-related projects.

The EPA's motion now rests with the U.S. Court of Appeals in Washington, D.C., where environmental organizations are preparing for a legal battle. The outcome could determine not only the fate of PFAS standards, according to Southerland, but also set a precedent for future drinking water protections under federal law.

“If [the EPA's legal] efforts are successful,” Southerland said. “It could be years before we see drinking water standards for these chemicals again. In the meantime, people will keep getting exposed.”