Overview

PFAS regulation in Ohio is a moving target. As of March 2026, there are two overlapping sets of numbers that consultants, water systems, and property owners need to understand: Ohio’s current PFAS Action Plan levels and the federal Maximum Contaminant Levels finalized in April 2024. Ohio has updated its Action Plan guidance to align with the federal MCLs - 4 ppt for PFOA and PFOS, and 10 ppt each for PFHxS, PFNA, and GenX. The federal MCLs are the enforceable standard for public water systems; Ohio’s Action Plan values are guidance only.

Ohio does not currently have state-specific enforceable PFAS cleanup standards for groundwater outside the drinking water context. There is no PFAS-specific rule under the Ohio Voluntary Action Program (OAC 3745-300), and BUSTR’s corrective action tables do not include PFAS compounds. For contaminated site work, consultants are generally screening against the federal MCLs for drinking water scenarios and EPA RSLs for non-drinking water scenarios.

Bottom line for consultants: If you’re doing site assessment or due diligence work in Ohio and PFAS is a potential concern, screen groundwater results against the federal MCLs (4 ppt for PFOA and PFOS). Ohio’s Action Plan guidance now matches the federal MCLs for PFOA and PFOS. If you encounter a reference to Ohio’s older “70 ppt” levels in legacy documents, those reflect the 2019 Action Plan and should not be used for current screening.

Federal PFAS MCLs (The Enforceable Standard)

In April 2024, EPA finalized the first-ever National Primary Drinking Water Regulation for PFAS. These are legally enforceable limits for public water systems.

PFAS Compound	MCL	MCLG	Status (as of March 2026)
PFOA	4 ppt	0	In effect - EPA confirmed it will keep this standard
PFOS	4 ppt	0	In effect - EPA confirmed it will keep this standard
PFHxS	10 ppt	10 ppt	Being rescinded - EPA announced intent to rescind
PFNA	10 ppt	10 ppt	Being rescinded - EPA announced intent to rescind
HFPO-DA (GenX)	10 ppt	10 ppt	Being rescinded - EPA announced intent to rescind
Hazard Index (PFHxS + PFNA + HFPO-DA + PFBS mixture)	HI = 1	HI = 1	Being rescinded - EPA announced intent to rescind

Key Compliance Dates

Public water systems must complete initial PFAS monitoring by 2027 and were originally required to comply with MCLs by 2029. EPA has announced plans to extend the PFOA/PFOS compliance deadline to 2031 to give water systems more time, with a proposed rule expected to be finalized in spring 2026.

What’s Being Rescinded and What’s Not

In May 2025, EPA announced that it will keep the PFOA and PFOS MCLs at 4 ppt but plans to rescind the MCLs for PFHxS, PFNA, HFPO-DA (GenX), and the Hazard Index mixture. EPA stated it will “reconsider the regulatory determinations” for those four compounds. The proposed rescission rule was expected in fall 2025, with finalization in spring 2026.

This means that as of this writing, the only PFAS compounds with confirmed, ongoing federal MCLs are PFOA and PFOS. The status of the other four is uncertain.

Ohio PFAS Action Plan Levels (Current)

Ohio’s PFAS Action Plan, originally released in December 2019 under Governor DeWine’s executive order, established action levels for PFAS in drinking water. These are guidance values - not enforceable regulatory standards - used to trigger response protocols when detected in public water systems. Ohio has updated its Action Plan guidance to align with the 2024 federal MCLs for PFOA, PFOS, PFHxS, PFNA, and GenX.

PFAS Compound	Ohio Action Level	Basis
PFOA	4 ppt	Aligned with federal MCL (updated from 70 ppt combined)
PFOS	4 ppt	Aligned with federal MCL (updated from 70 ppt combined)
PFHxS	10 ppt	Aligned with federal MCL (updated from 140 ppt)
PFNA	10 ppt	Aligned with federal MCL (updated from 21 ppt)
GenX (HFPO-DA)	10 ppt	Aligned with federal MCL (updated from 700 ppt)
PFBS	No Action Plan standard	Not included in updated guidance

Context on the Original 2019 Levels

The original 2019 Action Plan used 70 ppt combined for PFOA and PFOS (based on the U.S. EPA 2016 Health Advisory Level). If you encounter a reference to a “70 ppt” PFAS standard in Ohio legacy documents, it refers to those original 2019 action levels and is no longer current.

The absence of a PFBS action level in the updated guidance reflects the compound’s different toxicity profile - PFBS is considered far less toxic than PFOA or PFOS, and EPA is reconsidering its inclusion in the federal drinking water rule as part of the PFHxS/PFNA/GenX rescission process.

Practical Guidance for Site Assessment Work

Phase I ESAs

PFAS is increasingly relevant to Phase I Environmental Site Assessments in Ohio. Under ASTM E1527-21, the environmental professional must consider “emerging contaminants” when evaluating recognized environmental conditions. Properties with the following historical uses warrant PFAS attention:

Fire training facilities and airports (AFFF foam use)
Military bases (Wright-Patterson AFB in Dayton is a well-known Ohio PFAS site)
Chrome plating and metal finishing operations
Landfills, especially those that accepted industrial waste
Wastewater treatment plants
Properties near any of the above

Phase II ESAs - Which Numbers to Use for Screening

For Phase II sampling programs in Ohio where PFAS is a contaminant of concern:

Groundwater (drinking water scenario): Screen against the federal MCLs - 4 ppt for PFOA and 4 ppt for PFOS. For other PFAS compounds, use the most current EPA RSLs for tap water, though be aware that the regulatory status of PFHxS, PFNA, and GenX is in flux.

Groundwater (non-drinking water scenario): Use EPA RSLs for the appropriate exposure pathway. The vapor intrusion pathway is generally not a concern for PFAS (they’re not volatile), but the groundwater-to-surface-water pathway may need evaluation if a site is near a water body.

Soil: EPA RSLs include PFAS screening levels for residential and commercial/industrial soil. Ohio does not have state-specific PFAS soil standards under the VAP.

Important: PFAS analysis requires specialized sampling procedures. Standard sampling equipment used for VOCs and metals will contaminate PFAS samples. See our PFAS Sampling Best Practices guide for detailed field procedures.

BUSTR Sites

PFAS is not currently a chemical of concern under Ohio BUSTR’s corrective action rules (OAC 1301:7-9-13). The BUSTR COC tables (Tables 2.2 and 3.1 in the TGM) do not include any PFAS compounds. However, if AFFF foam was ever used at a petroleum UST site (fire suppression, training), PFAS may be present as a co-contaminant, and separate assessment under a different regulatory framework may be warranted.

Ohio VAP Sites

The Ohio VAP (OAC 3745-300) does not currently include PFAS-specific generic standards. For VAP-enrolled properties where PFAS is a concern, site-specific standards would need to be developed through the risk assessment process. Consultants working on VAP sites with PFAS should coordinate directly with Ohio EPA’s Division of Environmental Response and Revitalization (DERR).

Ohio PFAS Contamination - Key Sites

Several major PFAS contamination sites in Ohio have driven state and federal attention:

Wright-Patterson Air Force Base (Dayton): PFAS from AFFF firefighting foam has contaminated groundwater affecting the City of Dayton’s Miami Wellfield. Extensive investigation and monitoring is ongoing, with the city investing in treatment infrastructure.
DuPont Washington Works (Parkersburg, WV / Ohio border): The C-8 litigation - one of the largest PFAS cases in the country - stemmed from PFOA contamination of drinking water in Ohio communities along the Ohio River. Ohio reached a $110 million settlement with DuPont in November 2023.
Columbus and central Ohio: Multiple public water systems in the Columbus area detected PFAS during the statewide sampling program.

What to Watch

The PFAS regulatory landscape will continue to shift through 2026 and beyond. Key developments to monitor:

EPA spring 2026 rulemaking: The proposed rule extending PFOA/PFOS compliance deadlines and formally rescinding the other four PFAS MCLs could drop any time now.
CERCLA hazardous substance designation: EPA designated PFOA and PFOS as hazardous substances under CERCLA. This significantly expands liability at contaminated sites and will affect cleanup obligations at sites across Ohio.
Ohio state action: Ohio has not yet adopted state-specific PFAS MCLs or groundwater cleanup standards. If the state moves to adopt its own standards (as New Jersey, Michigan, and others have done), those could be stricter than or different from federal levels.
EPA RSL updates: EPA’s Regional Screening Levels for PFAS in soil and groundwater are updated periodically and serve as the de facto screening tool for site assessment work in Ohio.

Ohio EPA PFAS Information Page - State testing results and action plan documents
EPA PFAS Drinking Water Regulation - Federal MCL information and compliance guidance
EPA Regional Screening Levels (RSLs) (coming soon) - Federal screening levels including PFAS compounds
PFAS Sampling Best Practices - Field guide for collecting valid PFAS samples