State PFAS regulations stronger than EPA, MI, NJ, NH and others

The two-sentence version

Michigan, New Jersey, and New Hampshire each adopted enforceable PFAS Maximum Contaminant Levels (MCLs) years before the federal rule landed in April 2024, and Massachusetts, New York, and California followed with their own frameworks. The federal MCL is now tighter than most state MCLs for PFOA and PFOS, but state rules still bind utilities where they regulate compounds Washington skipped, Michigan's PFHxA and PFBS limits, for example, have no federal analogue.

The federal preemption question

Under the Safe Drinking Water Act, a federal National Primary Drinking Water Regulation (NPDWR) sets a floor. States that have been delegated primacy administer the federal rule and may set standards more stringent than the federal MCL, but never less. When the EPA finalised the PFAS NPDWR, codified at 40 CFR §141.61(c), 89 Fed. Reg. 32532, it pegged PFOA and PFOS at 4.0 nanograms per litre (ng/L, equivalent to parts per trillion) and PFHxS, PFNA, and HFPO-DA at 10 ng/L, with a Hazard Index of 1 for the mixture of the latter three plus PFBS.

That federal floor is, for PFOA and PFOS, lower than every existing state MCL. A Michigan utility that was previously meeting the state's 8 ng/L PFOA limit now has to plan for 4.0 ng/L compliance by 2029. But the state rules did not vanish. Where a state regulates a compound the federal rule does not (Michigan's PFHxA at 400,000 ng/L; Michigan's PFBS at 420 ng/L as a discrete MCL rather than only inside a Hazard Index), the state limit remains the binding number. Where the state's compound list and the federal list overlap, utilities must meet the lower of the two.

The practical effect: state PFAS regulation continues, but the centre of gravity has shifted to Washington. Compliance schedules now run on the federal calendar, initial monitoring by 2027, capital compliance by 2029, while state programmes that paved the way persist as wider safety nets.

Michigan, the most comprehensive state regime

Michigan's Department of Environment, Great Lakes, and Energy (EGLE), through the Michigan PFAS Action Response Team (MPART), set the most ambitious state PFAS regime in the United States. The rules, codified at R 325.10604g of the Michigan Administrative Code, took effect in August 2020 and regulate seven PFAS at the following enforceable levels:

• PFNA, 6 ng/L
• PFOA, 8 ng/L
• PFOS, 16 ng/L
• PFHxS, 51 ng/L
• PFHxA, 400,000 ng/L
• GenX (HFPO-DA), 370 ng/L
• PFBS, 420 ng/L

The numbers were derived by a state Science Advisory Workgroup using compound-specific oral reference doses and a drinking-water relative source contribution model. Michigan was explicit that the science panel set each MCL independently, the PFOA value, for instance, came out at 8 ng/L because the workgroup used a more conservative reference dose than the one the EPA was using in 2020. PFHxA's 400,000 ng/L looks shocking against its sibling compounds; that number reflects the much weaker toxicological evidence for PFHxA at the time, not a casual approach.

After April 2024, the federal floor takes over for PFOA, PFOS, PFHxS, PFNA, and HFPO-DA inside Michigan. The state's PFHxA and PFBS limits remain the binding standards because the federal rule does not assign them discrete MCLs, PFBS appears only as a component of the federal Hazard Index calculation, and PFHxA is not in the federal rule at all. For a Michigan utility, the compliance question is no longer "which rule applies" but "which number is lowest for this compound today."

New Jersey, first in the United States

The New Jersey Department of Environmental Protection (NJDEP) holds the historical first. In September 2018 New Jersey adopted an enforceable MCL for PFNA at 13 ng/L, the first state-level drinking-water MCL for any PFAS compound anywhere in the country. The rulemaking was the product of a long process by the state's Drinking Water Quality Institute, which had recommended a health-based maximum contaminant level for PFNA in 2015.

New Jersey followed in June 2020 with MCLs for the two more familiar compounds: PFOA at 14 ng/L and PFOS at 13 ng/L. Those numbers, again, came out of a health-based derivation by the Drinking Water Quality Institute and were set independently of any federal guidance. As of April 2024, the federal 4.0 ng/L MCL on PFOA and PFOS preempts the higher state values, but the New Jersey PFNA limit of 13 ng/L remains operative, it is more stringent than the federal 10 ng/L PFNA MCL.

New Jersey also pioneered the use of MCLs as a basis for state cleanup and source-control actions, with the Department citing the same drinking-water values when issuing directives to PFAS-discharging facilities. That linkage between drinking-water standards and source-water enforcement is something the federal rule does not directly create; it remains a feature of how New Jersey administers the programme.

New Hampshire, four MCLs, a legal challenge, and a re-adoption

The New Hampshire Department of Environmental Services (NHDES) adopted four PFAS MCLs in 2019 under RSA 485:16-e:

• PFOA, 12 ng/L
• PFOS, 15 ng/L
• PFHxS, 18 ng/L
• PFNA, 11 ng/L

The rules were challenged in state court, primarily over the cost-benefit analysis behind them, and a Merrimack County Superior Court order in late 2019 enjoined enforcement. The legislature responded by amending the underlying statute, and NHDES re-adopted the same four MCLs in 2020 on the strengthened statutory footing. The numbers themselves were unchanged.

Of New Hampshire's four MCLs, the PFNA limit at 11 ng/L remains the binding standard inside the state after April 2024, because it is more stringent than the federal 10 ng/L value… actually, the federal value is the lower of the two for PFNA, so the federal floor takes effect. The same applies to PFOA, PFOS, and PFHxS, the federal MCLs are lower across the board. New Hampshire's state programme continues to handle monitoring, reporting, and enforcement; the numeric thresholds it enforces against utilities are now the federal ones for these four compounds.

Massachusetts, a sum-of-six approach

The Massachusetts Department of Environmental Protection (MassDEP) took a structurally different route. Rather than set a per-compound MCL, MassDEP adopted in October 2020 a single MCL for the sum of six PFAS at 20 ng/L: PFOA, PFOS, PFHxS, PFNA, PFHpA, and PFDA. The rule is codified at 310 CMR 22.07G.

The sum-of-six method captures co-occurring PFAS that individual MCLs can miss. A water that contains 4 ng/L of each of the six compounds, well under any single-compound state MCL elsewhere, would total 24 ng/L and exceed Massachusetts' summed limit. After April 2024, Massachusetts utilities must meet both the federal per-compound MCLs (and the federal Hazard Index for the mixture of PFHxS, PFNA, HFPO-DA, and PFBS) and the state's sum-of-six standard. For some source waters, the binding constraint is now federal; for others, the Massachusetts sum is what triggers treatment.

New York, paired 10 ng/L MCLs

The New York State Department of Health adopted MCLs for PFOA and PFOS in July 2020, each at 10 ng/L, under 10 NYCRR Subpart 5-1. New York also added a 1,4-dioxane MCL in the same rulemaking, broadening the state's chemical contaminant programme.

The 10 ng/L number sat between New Jersey's 14 ng/L for PFOA and New Hampshire's 12 ng/L when it was adopted, moderate by state standards at the time. After April 2024 the federal 4.0 ng/L MCL preempts the New York values for both compounds. The state programme continues to administer monitoring, public notification, and enforcement; the operative numeric thresholds are now federal.

California, Notification and Response Levels, not MCLs

California has not adopted a formal MCL for PFOA or PFOS. The State Water Resources Control Board's Division of Drinking Water instead uses a two-tier framework of Notification Levels (NLs) and Response Levels (RLs). Notification Levels trigger reporting to local governing bodies and recommended public notification; Response Levels trigger a recommendation to take the source out of service or treat it. Neither is, strictly, an MCL.

The current values, set in 2019 with subsequent updates:

• PFOA Notification Level, 5.1 ng/L
• PFOS Notification Level, 6.5 ng/L
• Response Level (combined), 10 ng/L

The framework is quasi-enforceable: utilities are not legally barred from delivering water above an NL, but the state expects notification, public disclosure, and, at or above the RL, source removal or treatment. California is in active rulemaking on formal MCLs; the state's Office of Environmental Health Hazard Assessment (OEHHA) has published Public Health Goals for PFOA and PFOS in the sub-nanogram-per-litre range, which feed the state's MCL derivation.

Vermont, Connecticut, Pennsylvania, for context

Vermont adopted in 2020 an MCL for the sum of five PFAS (PFOA, PFOS, PFHxS, PFHpA, PFNA) at 20 ng/L, a sum-of-five variant of the Massachusetts approach. Connecticut has operated on action levels rather than MCLs, with the state Department of Public Health setting action levels of 16 ng/L for PFOA and 10 ng/L for PFOS. Pennsylvania adopted MCLs of 14 ng/L for PFOA and 18 ng/L for PFOS in early 2023, late in the state-rulemaking wave and immediately superseded by the federal rule the following year.

None of these state numbers is more stringent than the federal April 2024 PFOA/PFOS limits, but each state's broader programme, sampling cadence, public notification, source assessments, continues to operate. The pattern is the same everywhere: states built the architecture; the federal rule now provides the binding numerical floor for the five compounds it regulates.

Comparison table, state PFAS MCLs vs the federal April 2024 NPDWR

All values in ng/L (parts per trillion). Empty cells indicate no enforceable per-compound MCL in that jurisdiction.

NL = Notification Level (not a true MCL). AL = Action Level (not a true MCL). HI = part of the federal Hazard Index calculation rather than a discrete MCL.

What this means for a customer of a US public water system

If you live in Michigan, New Jersey, or any of the other states with adopted MCLs, your utility has been monitoring for PFAS, and reporting against an enforceable number, for several years already. The federal April 2024 rule reshapes that picture: it lowers the legal threshold for PFOA and PFOS to 4.0 ng/L nationwide, with utility compliance required by 2029 under the current schedule. Where state rules cover compounds the federal rule does not (Michigan's PFHxA limit, for instance), the state number still binds.

None of this changes what a household can do at the tap. The federal MCL, like every state MCL, applies at the point where water leaves the utility's treatment plant. If your concern is what comes out of the kitchen sink, a household filter certified to NSF/ANSI 53 with the P473 protocol or an NSF/ANSI 58 reverse-osmosis system is what materially removes PFAS, regardless of which agency drew the regulatory line.

Related guides

• EPA's April 2024 PFAS MCL, what 4 ng/L actually means
• UCMR 5 explained, what the utility data does and doesn't say
• PFAS groundwater hotspot map, the documented contamination zones
• The C8 Science Panel and DuPont, where the PFOA epidemiology came from
• Home PFAS testing labs, what you actually get for $200–$500

Sources

1. Michigan Administrative Code, R 325.10604g, Michigan PFAS Maximum Contaminant Levels (adopted August 3, 2020). Administered by Michigan EGLE and the Michigan PFAS Action Response Team (MPART).
2. New Jersey Department of Environmental Protection, N.J.A.C. 7:10, PFNA MCL 13 ng/L (adopted September 4, 2018); PFOA MCL 14 ng/L and PFOS MCL 13 ng/L (adopted June 1, 2020). New Jersey Drinking Water Quality Institute Health-Based MCL recommendations.
3. New Hampshire RSA 485:16-e and Env-Dw 700, PFOA 12 ng/L, PFOS 15 ng/L, PFHxS 18 ng/L, PFNA 11 ng/L (originally adopted 2019; enjoined; re-adopted under amended statute in 2020).
4. 40 CFR §141.61(c), PFAS National Primary Drinking Water Regulation, finalised April 10, 2024 and published 89 Fed. Reg. 32532 (April 26, 2024). PFOA 4.0 ng/L, PFOS 4.0 ng/L, PFHxS 10 ng/L, PFNA 10 ng/L, HFPO-DA 10 ng/L, plus Hazard Index = 1 for the mixture of PFHxS, PFNA, HFPO-DA, and PFBS.
5. Massachusetts Department of Environmental Protection, 310 CMR 22.07G, Sum-of-six PFAS MCL at 20 ng/L (adopted October 2, 2020).
6. New York State Department of Health, 10 NYCRR Subpart 5-1, PFOA MCL 10 ng/L, PFOS MCL 10 ng/L (adopted July 30, 2020).
7. California State Water Resources Control Board, Division of Drinking Water, PFOA Notification Level 5.1 ng/L, PFOS Notification Level 6.5 ng/L; combined Response Level 10 ng/L (2019, with subsequent updates).
8. Vermont Department of Environmental Conservation, sum-of-five PFAS MCL at 20 ng/L (2020).
9. Connecticut Department of Public Health, drinking water action levels for PFOA and PFOS.
10. Pennsylvania Department of Environmental Protection, PFOA MCL 14 ng/L, PFOS MCL 18 ng/L (adopted January 2023).

Last reviewed: 30 June 2026 · How Safe Is My Water editorial. Regulatory citations verified against state administrative codes and the Federal Register. This guide is an educational summary; it is not legal advice and does not represent any agency's position.