Federal Retreat, State Advance: What EPA’s Proposed PFAS Drinking-Water Rollback Means for Arizona

By Patrick J. Paul, John Habib, and Sukhmani K. Singh

EPA is moving to scale back the PFAS drinking-water standards it finalized in 2024 — rescinding limits for four compounds outright and buying utilities two more years to meet the two that remain. The comment period on EPA’s proposed rulemaking closed July 20, 2026, and a final rule is expected by year-end. For Arizona water systems, the practical takeaway is counterintuitive: a federal rollback does not mean the PFAS problem is going away, and in some respects, compliance and litigation exposure is getting more complicated, not less.

EPA’s Proposal

In April 2024, EPA finalized a National Primary Drinking Water Regulation setting the first-ever enforceable limits — Maximum Contaminant Levels, or MCLs — for six PFAS compounds. Two of them, PFOA and PFOS, were set at 4 parts per trillion each. The other four (PFHxS, PFNA, GenX/HFPO-DA, and a Hazard Index for mixtures) rounded out the package. Public water systems were given until 2027 to complete initial monitoring and until April 2029 to install treatment where results exceeded the limits.

On May 18, 2026, EPA proposed unwinding much of that framework through two rules:

The comment period for both proposals closed July 20, 2026, and EPA has signaled its intent to finalize before the end of the year. Separately, litigation over the original 2024 standards remains pending in the D.C. Circuit, where the court earlier this year declined EPA’s request to sideline the challenges to the very PFAS limits the agency now wants to repeal — a reminder that the rulemaking and the litigation are proceeding on parallel, but not fully aligned, tracks.

No Reprieve for Arizona

Here is the part that matters for Arizona businesses: Arizona does not create its own PFAS drinking-water standard. ADEQ adopts the federal drinking-water rules by reference — codified in Title 18, Chapter 4 of the Administrative Code — precisely to retain primary enforcement authority over the Safe Drinking Water Act in the state. That structural choice cuts two ways. It means Arizona’s enforceable floor generally tracks whatever EPA lands on, so a federal rescission would pull the state standard down with it. But it also means Arizona water systems remain squarely inside a federal compliance regime that, for PFOA and PFOS, is being delayed rather than dismantled. The obligation is not disappearing; its timeline is shifting.

The underlying contamination is real. ADEQ’s statewide sampling found that roughly one in ten tested public water systems exceeded at least one PFAS limit — not a trivial share in a state exceedingly dependent on groundwater. ADEQ already has funded interconnection and treatment fixes in communities such as Globe, Star Valley, and Payson, drawing on a mix of state appropriations and federal infrastructure dollars. These problems are not resolved simply by extending the compliance date.

Meanwhile, Arizona is moving in the opposite direction from the federal government on a different PFAS front. Effective September 12, 2026, Arizona’s HB 2641 will prohibit the use or discharge for training and testing purposes of Class B firefighting foam containing intentionally added PFAS – by private parties, local governments, and state agencies alike – unless a federal regulation requires otherwise. Airports, fire districts, industrial facilities, and defense-adjacent operations that still train with legacy aqueous film-forming foam need to transition by then. Airports, fire districts, and other aqueous film-forming foam users should confirm inventory, training protocols, and disposal pathways now.

For public water systems and municipalities, the extension may relieve near-term budget pressure on PFOA and PFOS treatment, but these entities should continue monitoring and capital planning on the original track. Rate-case timing, bond schedules, and grant applications built around a 2029 deadline should not be quietly rebuilt around 2031 while the rule is still just a proposal and litigation is pending.

For industrial and permitted dischargers, drinking-water MCLs are only one consideration. EPA’s broader PFAS agenda still contemplates effluent guidelines and NPDES monitoring obligations, and CERCLA exposure for PFOA and PFOS remains unaffected. A drinking-water rollback does not translate to a release from liability.

The federal PFAS drinking-water standard is contracting, but the compliance and liability landscape in Arizona is not simplifying. State primacy ties Arizona to federal MCLs even as those MCLs are in flux; documented contamination persists regardless of the standard; and Arizona’s own PFAS legislation is tightening on a separate track. Clients who read “EPA rollback” as “PFAS is over” will be making decisions on a premise that the facts on the ground do not support.