Per- and Polyfluoroalkyl Substances (PFAS) in Drinking Water

[Last Update: June 13, 2025]

As an important note: while the PFAS MCLs are not yet enforceable, PWSs should be using this time to determine if they have PFAS and what approach they will take to comply with the MCLs.

Per- and Polyfluoroalkyl Substances (PFAS) are a class of thousands of man-made chemicals with unique physical and chemical properties. Historically, PFAS have been used in several consumer goods and industry products, including nonstick cookware, water-resistant clothes, and stain-resistant fabrics. These compounds have been found to exist and persist in the environment and current science has linked long-term exposure of certain PFAS to cancer and other illnesses. While drinking water is not the only exposure pathway, or way that a person can come into contact with a hazardous substance, it does represent one potential source.

The federal PFAS rule for drinking water was first published April 26, 2024, and it applies to Community and Non-Transient Non-Community (NTNC) Public Water Systems (PWSs). The rule sets the Maximum Contaminant Levels (MCLs), Trigger Levels, and Practical Quantitation Levels (PQLs) for various PFAS at the following, including the use of a Hazard Index (HI):

Regarding units, note that parts per trillion (ppt) is equal to nanograms per liter (ng/L). Additionally, PQL is defined as the lowest concentration of a contaminant that can be reliably achieved within specified limits of precision and accuracy during routine laboratory operating conditions. The uses and relevant resource documents for MCLs, Trigger Levels, and PQLs are found below. Generally, MCLs are used in compliance calculations and schedule determinations, PQLs are used in compliance calculations, and Trigger Levels are used for schedule determinations.

On May 14, 2025, U.S. EPA announced intent to extend compliance deadlines for PFOA and PFOS proposing an extension of two years (to 2031). This announcement also included the “intent to rescind the regulation and reconsider the regulatory determinations for PFHxS, PFNA, HFPO-DA (commonly known as GenX), and the Hazard Index…” Ohio EPA will update this webpage as more information becomes available.

With the passing of the federal rule, Ohio EPA has begun its rulemaking process. Ohio EPA is not currently planning any requirements more stringent than those in the federal rule.

Current Status:

• Early Stakeholder Outreach (ESO): complete
  • Comments were accepted through close of business Sept. 20, 2024
• Rule Filing Process: in progress
  • After considering ESO comments, Ohio EPA started the rule filing process required by the Joint Committee on Agency Rule Review (JCARR)
  • Due to U.S. EPA’s May 2025 announcement, Ohio EPA is evaluating the next steps in the rulemaking process

General Resources:

• PFAS Overview
  • U.S. EPA PFAS Overview
• External Fact Sheets and Webinars
  • U.S. EPA PFAS Resources
• Current PFAS Actions in Ohio
  • Ohio EPA’s PFAS Action Plan Webpage

Common Questions:

• Is there a list of acceptable labs for PFAS analysis?

  • Ohio EPA has prepared a list of state-certified or accepted labs with PFAS capabilities. The acceptable labs for PFAS have PFAS listed in the Other column.

• What financial resources are available for PFAS in drinking water?

• • Ohio EPA has general technical assistance options for systems with a population under 10,000. U.S. EPA provides PFAS-specific technical assistance to a smaller group of systems. Reach out directly to Gina.Hayes@epa.ohio.gov for more information.
  • Ohio EPA also offers low/no interest loans and potential principal forgiveness through the WSRLA program.

Initial Monitoring

[This is subject to all changes at the federal level]

By April 26, 2027, Community and NTNC PWSs must complete initial monitoring. This includes sampling, reporting results to Ohio EPA, and providing results to customers in their CCRS (delivered by July 1, 2027). The sampling requirements can be satisfied using any of the following options: collect new samples, substitute existing data from acceptable sources, or use a combination of the two. To satisfy the initial monitoring requirements, PWSs must have a total of either two or four samples, depending on source water type and system size. 

The results of initial monitoring will determine the schedule at which PWSs will begin compliance monitoring in 2027. Due to the low trigger levels and potential for contamination of samples, Ohio EPA encourages PWSs to complete sampling in a timely manner.

For more information, refer to the:

• PFAS Initial Monitoring fact sheet.

To submit data to Ohio EPA, as described in the above fact sheet, labs may use the provided spreadsheet (or otherwise create an XML file) or enter data into the eDWR online form. The spreadsheet and data submission instructions, including how to create an eBiz account, are available below:

• PFAS Data Submission Spreadsheet
• Instructions for PFAS Data Submission.

Common Questions

How many total samples must a PWS collect for initial monitoring?

Initial monitoring requires a total of either two or four samples, depending on system size and water source (see Table 1 of the PFAS Initial Monitoring fact sheet). Systems with UCMR 5 or other qualifying samples may be able to fully or partially substitute those results. If no resampling is needed for initial monitoring, no additional PFAS samples will be required until compliance monitoring begins in 2027.

How does a PWS know if they have completed initial monitoring?

Ohio EPA will periodically send updates via email (mail@notify.onecallnow.com) that list each PWS’s monitoring status and whether additional information is needed.

How does initial monitoring affect compliance schedules?

Initial monitoring results will determine compliance monitoring schedules in 2027. Quarterly monitoring will be required if an EP sample result is at or above any trigger level. Triennial monitoring will only be allowed if all samples are below all trigger levels. Future compliance monitoring schedules may be reduced if results remain consistently low.

What happens if a PWS does not complete initial monitoring?

Failure to complete sampling, reporting, and CCR requirements by April 26, 2027 will result in a monitoring/reporting violation. Avoid violations by ensuring all requirements are met on time.

For Labs: How does the Copy/Paste feature in eDWR work?

Additional details are available in the “Instructions for PFAS Data Submission”, linked in the above section.

Messaging and Risk Communication

With the increased spotlight on PFAS, PWSs may receive questions from customers about their drinking water. For health questions and concerns, Ohio EPA recommends contacting a physician or the Ohio Department of Health (ODH).

Ohio EPA is currently developing a PFAS Messaging and Risk Communication fact sheet which will be posted here to assist with communication strategies, including common questions relating to PFAS messaging.

Compliance Monitoring

Ohio EPA is reviewing the May 2025 announcement to determine how U.S. EPA’s intent to make changes to the existing federal rules will affect compliance monitoring.

The current final rule (published April 26, 2024) requires PWSs to complete compliance monitoring beginning on April 26, 2027. Initial schedules will either be quarterly (four times each year) or triennial (once every three years), depending on the results of initial monitoring. Beyond 2027, there are opportunities to reduce monitoring by having consistent results below the MCLs (annual) and below the trigger levels (triennial). Ohio EPA encourages PWSs to complete sampling in a timely manner, allowing leeway for potential re-sampling (should it become necessary).

More information will be available through the PFAS Compliance Monitoring fact sheet, which is currently under development.

MCL Compliance

Ohio EPA is reviewing the May 2025 announcement to determine how U.S. EPA’s proposal to extend compliance deadlines by two years (to 2031) will affect MCL compliance.

The current final rule (published April 26, 2024) requires PWSs to comply with the PFAS MCLs beginning on April 26, 2029. This may require installing treatment or the use of alternative sources (connecting to another PWS, well changes, etc.). In the case of exceedances, PWSs will be required to public notice.

More information will be available through the PFAS Compliance Calculations fact sheet, which is currently under development.