EPA Finalizes PFAS Drinking Water Rule

On April 10, 2024, EPA announced the final rule for six PFAS in drinking water and will host a series of public webinars to provide more information. This final National Primary Drinking Water Regulation (NPDWR) establishes individual Maximum Contaminant Levels (MCLs) of 4.0 ppt for PFOA and PFOS, and 10 ppt for PFHxS, PFNA, and HFPO-DA (known as GenX chemicals). The NPDWR also sets a Hazard Index (HI) MCL of 1 (unitless) to account for dose-additive health effects for two or more combined and co-occurring levels of PFHxS, PFNA, and HFPO-DA, as well as PFBS.

The changes from the March 2023 proposed rule include:

  • The addition of the individual MCLs of 10 ppt for PFHxS, PFNA, and HFPO-DA.
  • A change in the calculation of the HI MCL for two (changed from one) or more PFAS, and the change of the HI calculation denominator for PFHxS, from 9 ppt to 10 ppt.
  • A change in the trigger level for reduced monitoring from 1/3, to now 1/2 the final MCLs. Note: the trigger level calculations use specific values from the laboratory sample results, even when below the Practical Quantitation Level (PQL).
  • A provision for a two-year capital improvement timeframe in the final rule. The requirements for MCL compliance and public notification for MCL violations will now start five years following rule promulgation, with three years to complete initial monitoring.

Some additional items of note in the final rule:

  • Calculations for running annual averages for compliance determinations must use zeros for results below the PQLs – see the monitoring and reporting fact sheet.
  • The final rule does not allow primacy agencies to issue monitoring waivers or use composite samples.
  • The final rule does not allow the use of POU devices for MCL compliance, but notes they may be considered in the future if standards are updated and devices become available for removing PFAS to the appropriate MCLs.
  • Monitoring will not be required at system interconnection points for consecutive systems. Wholesale systems will be responsible for monitoring requirements at the entry point to the distribution system.

EPA is hosting a series of webinars about the final rule this month, each from 2:00 to 3:00 EDT:

The Agency is also making $1 billion in funding from the Bipartisan Infrastructure Law available annually through FY2026 for the Emerging Contaminants in Small or Disadvantaged Communities (EC-SDC) Grant Program. This funding is to help states and territories implement PFAS testing and treatment at public water systems and may also be used to help owners of private wells address PFAS contamination.

Visit EPA’s website to view the rule summary, fact sheets, a communications toolkit, and the Pre-Publication Federal Register Notice and technical support documents. To learn about ASDWA’s perspectives, read our Statement on Final PFAS Drinking Water Standards and our May 2023 Comments on the Proposed PFAS Rule. ASDWA will continue to review the details of the rule and work with our members, EPA, and partners on implementation of the final rule moving forward.