On April 8, 2024, the EPA Administrator signed the final rule establishing drinking water standards, also known as MCLs, for six PFAS (PFOA, PFOS, PFNA, GenX (HFPO-DA), PFHxS, and PFBS).  The final MCLs for PFOA and PFOS are the same as the level set forth in the proposed rule, 4 ppt.  The final rule also incorporates the combined Hazard Index of 1 for any mixture containing two or more of PFNA, GenX, PFHxS, and PFBS. However, the final rule also establishes individual MCLs, each at 10 ppt for PFNA, GenX, and PFHxS.

The final MCLs require public water systems to:

  • conduct initial monitoring within three years of the effective date of the final rule;
  • conduct public notification and include PFAS information in their Consumer Confidence Reports; and
  • make any necessary capital improvements to comply with the new MCLs within five years of the effective date of the final rule.

Under the final rule, community water systems will be required to report detected PFAS in their annual Consumer Confidence Reports and, if an MCL is exceeded, provide health effects language in the report.  Additionally, under the final rule, MCL violations require public notification as soon as practicable but no later than 30 days after a community water system learns of the violation. The final rule follows extensive public comment with EPA receiving more than 120,000 comments on the proposed rule.  The final rule is effective 60 days after the date of publication in the Federal Register.