PFAS Drinking Water Standards: How State Regulations Are Diverging from Federal Rules

On April 10, 2024, the EPA finalized its first-ever National Primary Drinking Water Regulation for six PFAS compounds, setting enforceable maximum contaminant levels for the first time (Stone, 2026). Less than a year later, the regulatory picture had changed considerably. The compliance deadline for PFOA and PFOS was pushed to 2031, the MCLs for four other compounds were slated for rescission, and an active federal lawsuit threatened to reshape the standards further. Meanwhile, more than 20 states had already set their own PFAS drinking water limits, and hundreds of new bills were moving through statehouses across the country.

For water treatment professionals, the practical question is straightforward: what PFAS levels does my system need to meet, and when? The answer now depends on jurisdiction, and the gap between the most and least restrictive states is measured in orders of magnitude.

The Federal Standard: Where It Stands

The EPA's April 2024 NPDWR established MCLs for six PFAS: PFOA, PFOS, PFHxS, PFNA, HFPO-DA (GenX), and a hazard index for mixtures of PFHxS, PFNA, HFPO-DA, and PFBS. The rule required public water systems to complete initial monitoring within three years and begin informing the public of PFAS levels by 2027 (Stone, 2026). Compliance with the MCLs was originally set for 2029 (Ajasa, 2025).

In May 2025, EPA affirmed the 4 parts per trillion MCLs for PFOA and PFOS but announced it would delay the compliance deadline for those two compounds to 2031 (BCLP, 2026). At the same time, EPA announced plans to rescind the MCLs for the other four PFAS chemicals and reexamine the regulatory determinations behind them (Stone, 2026).

EPA Administrator Lee Zeldin stated: "We are on a path to uphold the agency's nationwide standards to protect Americans from PFOA and PFOS in their water... [and] we will work to provide common-sense flexibility in the form of additional time for compliance" (Stone, 2026).

The situation is further complicated by active litigation. In American Water Works Association v. EPA, pending before the D.C. Circuit Court of Appeals, water utility petitioners argue that "EPA did not rely on the best available science and the most recent occurrence data" when establishing the 2024 MCLs (BCLP, 2026). On September 11, 2025, EPA moved to vacate portions of its own rule through this litigation, consistent with its plan to rescind the non-PFOA/PFOS standards (BCLP, 2026).

The Safe Drinking Water Act includes an anti-backsliding provision that prohibits the EPA from weakening drinking water standards once they have been set (Stone, 2026). In practice, the agency is asking the court to do what it is not permitted to do directly.

States Are Setting Their Own Limits

While federal standards shift, states have been moving ahead independently. In 2025 alone, over 350 PFAS-related bills were introduced across 39 states, with legislation enacted in five of them (Stone, 2026). The Washington Post reported that at least 250 of those bills were introduced in approximately 36 states specifically to address PFAS through product bans, drinking water limits, and cleanup funding (Ajasa, 2025).

As of January 2026, at least 20 states have adopted some form of regulatory standard for PFAS in drinking water (BCLP, 2026). Twenty-six states still have no state-specific PFAS drinking water regulations at all. Those states are Alabama, Arizona, Arkansas, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, North Dakota, Oklahoma, Oregon, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, and Wyoming (BCLP, 2026).

The variation among states that do regulate is substantial. According to BCLP's state-by-state analysis, state PFAS concentration limits range from 0.00266 ppt for PFOA in Nevada to 400,000 ppt for PFHxA in Michigan. Twenty states have adopted standards below 70 ppt. Four states (Alaska, Colorado, New Mexico, and Wisconsin) have set limits at 70 ppt. Several states appear in multiple regulatory categories because they have adopted different limits for different PFAS compounds (BCLP, 2026).

Compliance Note: Some states have laws requiring their drinking water standard to be no more stringent than the federal standard. As Steven Elmore, chair of the National Drinking Water Advisory Council, noted: "Certain states have state laws that say their drinking water standard can't be more stringent than the federal law" (Ajasa, 2025). If the federal MCLs for the four non-PFOA/PFOS compounds are rescinded, those states face a legal bind.

State-Level Action: Specific Examples

Maine passed legislation in June 2025 establishing a 4 ppt limit for PFOA and PFOS in drinking water, along with a 10 ppt limit for PFHxS, PFNA, and GenX, and additional limits for mixtures of those compounds. State Rep. Dan Shagoury, who introduced the bill, described it as a safeguard: "It's going to be up to the states to set limits in the absence of federal standards" (Ajasa, 2025).

Delaware enacted a new law that creates a monitoring and reporting dashboard so residents can find out the concentrations of PFAS in their drinking water. The dashboard is funded primarily by settlement money from litigation against chemical companies. State Sen. Darius Brown noted: "We'll do the work here locally to protect residents in our state to make sure that we have the proper reporting and that residents are informed around forever chemicals" (Ajasa, 2025).

Minnesota has taken one of the broadest approaches through "Amara's Law" (Minn. Stat. §116.943), which combines mandatory reporting obligations to the Minnesota Pollution Control Agency with phased prohibitions on the sale of products containing PFAS. Starting in 2032, a general ban will apply to all products containing PFAS unless the use is found to be "currently unavoidable" (Stone, 2026).

New Mexico classified PFAS as hazardous waste following a lawsuit against the U.S. Air Force. Firefighting foam from an air base caused a four-mile PFAS plume near Clovis, contaminating drinking water, crops, and poisoning farm animals. The state's new law classifying PFAS as hazardous waste is intended to support remediation efforts and protect residents (Ajasa, 2025).

Several additional states are in various stages of rulemaking. Florida, Illinois, and Virginia have enacted legislation to establish MCLs or statewide target levels that are not yet fully promulgated. Arizona, California, Georgia, Idaho, and South Carolina have proposed drinking water requirements for PFAS that have not yet been finalized (BCLP, 2026).

Beyond Drinking Water: The Wastewater Angle

The regulatory divergence extends beyond drinking water. On January 21, 2025, the Office of Management and Budget withdrew the EPA's proposed Effluent Limitations Guidelines for PFAS manufacturers under the Clean Water Act. That rule would have established technology-based effluent limitations for manufacturers in the Organic Chemicals, Plastics, and Synthetic Fibers category using best available control technologies (Barbour and Gross, 2025).

Without that federal rule, wastewater treatment plants and the sewage sludge they produce remain vulnerable to PFAS contamination (Barbour and Gross, 2025). States have begun using their authority under the National Pollutant Discharge Elimination System to fill this gap. Michigan's Department of Environmental Quality introduced specific PFAS limits in state NPDES permits for wastewater treatment plants and industrial facilities. Maine and New York implemented their own PFAS discharge limits through NPDES programs, targeting paper mills, textile manufacturers, and other potential PFAS sources (Barbour and Gross, 2025).

The Patchwork Problem

The current regulatory landscape creates real operational challenges. Water utilities that serve communities in multiple jurisdictions may face different PFAS standards depending on which state they operate in. Companies that discharge to waterways regulated under NPDES permits face similar inconsistencies.

The American Chemistry Council has warned about the consequences of fragmented regulation. Erich Shea, the ACC's director of product communications, stated: "The consequences could be skyrocketing prices, products no longer available in certain states and business opportunities moving from one state to another or overseas" (Ajasa, 2025).

The Association of Metropolitan Water Agencies, which sued the EPA over the original Biden-era NPDWR, has taken a more measured position. CEO Tom Dobbins stated: "AMWA continues to advocate for sound federal regulation of contaminants that pose nationwide threats, but otherwise we believe states are well positioned to regulate contaminants that are of regional concern" (Ajasa, 2025).

The compliance cost question is significant regardless of the regulatory tier. The EPA announced that compliance with the NPDWR would cost about $1.5 billion annually, though some industry analysts estimate the actual figure to be closer to $3.8 billion (Stone, 2026). On the other side of the ledger, a study by NYU Langone researchers examining roughly 5,000 Americans identified 13 medical conditions attributable to PFAS exposure. The resulting economic burden was estimated at a minimum of $5.5 billion up to $63 billion annually (Stone, 2026).

What This Means for Treatment Design

For water treatment professionals, the practical implications of this regulatory patchwork are concrete. A utility in Maine designing for 4 ppt PFOA/PFOS and 10 ppt for PFHxS, PFNA, and GenX faces a fundamentally different engineering challenge than a system in a state with no PFAS standards at all. And a facility in Michigan, where state NPDES permits include specific PFAS discharge limits, needs to account for both influent treatment and effluent compliance.

Several factors are worth tracking:

Design to the strictest applicable standard. Systems in states with active PFAS legislation should size treatment infrastructure for the most restrictive limit they may need to meet. With states continuing to introduce new bills and several states in active rulemaking, the regulatory floor in any given jurisdiction may drop before existing equipment reaches the end of its service life.

Monitor the federal litigation. The outcome of American Water Works Association v. EPA in the D.C. Circuit will determine whether the 4 ppt MCLs for PFOA and PFOS survive in their current form. That ruling will also affect what states tied to federal standards can require of their own utilities.

Account for the full PFAS profile. Even if federal standards narrow to PFOA and PFOS only, states like Maine and Minnesota have already set limits on additional compounds. Treatment systems that target only two compounds may face costly retrofits as state regulations expand. For guidance on how different media perform across the PFAS spectrum, see our analysis of GAC vs. ion exchange performance for short-chain compounds.

Factor in long-term health cost data. The NYU Langone economic burden estimates ($5.5 billion to $63 billion annually from PFAS-attributable health conditions) provide context for treatment investment decisions, particularly for utilities serving communities with documented PFAS exposure. For a detailed review of the health science, see our article on PFAS health risks and the EPA's 2026 regulatory posture.

The regulatory landscape for PFAS in drinking water is moving in two directions at once. Federal standards are contracting while state standards are expanding. Water utilities and treatment providers operating across jurisdictions will need systems flexible enough to meet the strictest standard they face today and adaptable enough for standards that have not been finalized yet.

Sources

1. Stone, B. (2026). "Forever Chemicals: The Shifting Landscape of PFAS Regulation." University of Cincinnati Law Review Blog, Vol. 94. https://uclawreview.org/2026/03/12/forever-chemicals-the-shifting-landscape-of-pfas-regulation/
2. Ajasa, A. (2025). "As EPA weakens rules on 'forever chemicals,' states are moving forward." The Washington Post. https://www.washingtonpost.com/climate-environment/2025/08/01/pfas-forever-chemicals-states/
3. Barbour, M. and Gross, B. (2025). "The Withdrawal of PFAS Effluent Limits: Implications for Federal Environmental Regulation and Biosolids Management." JD Supra / MG+M The Law Firm. https://www.jdsupra.com/legalnews/the-withdrawal-of-pfas-effluent-limits-5649612/
4. CAS Science Team (2025). "The PFAS landscape: Understanding regulations, applications, and alternatives." CAS / American Chemical Society. https://www.cas.org/resources/cas-insights/pfas-landscape
5. Brooks, E.L., Dempsey, J.B., Bromley, C., and Ravenborg, D. (2026). "PFAS Drinking Water Standards: State-By-State Regulations." Bryan Cave Leighton Paisner LLP. Updated January 2026. https://www.bclplaw.com/en-US/events-insights-news/pfas-drinking-water-standards-state-by-state-regulations.html