Proposed: First Federal Limits on PFAS in Drinking Water

Posted on 3/29/2023 by Nick Waldron and Roger Marks

Update 03/29/2023

US EPA's proposed rule to establish enforceable drinking water standards for six per- and polyfluoroalkyl substances (PFAS) appeared in the Federal Register on March 29, 2023. 

EPA will accept public comments until May 30, 2023 and will hold a public hearing about the proposed rule on May 4, 2023. 

drinking water standards for PFAS from US EPA March 2023

The proposed rule doubles as a "preliminary regulatory determination" that, for four of the six substances—PFNA, PFHxS, PFBS, and "Gen X chemicals," limits are  EPA decided years ago that PFOA and PFOS should carry a Maximum Contaminant Level or MCL under the Safe Drinking Water Act (SDWA).

More recently, EPA included PFAS (as a category) on its fifth Contaminant Candidate List (CCL 5), released in November 2022.

Once EPA lists a contaminant on the CCL, the agency must determine whether or not to limit the concentration of that substance in drinking water. The statutory criteria behind this "regulatory determination" include potential adverse health effects, the level and frequency of contamination, and ramifications for public water systems. 

See the proposed PFAS drinking water standards here.

(Posted 03/15/2023)

US EPA is proposing drinking water limits for six per- and polyfluoroalkyl substances (PFAS). The regulation would create the nation’s first-ever national limits for a widely used class of substances nicknamed “forever chemicals” because they do not break down over time.

The proposed rule would establish Maximum Contaminant Levels (MCLs) for these PFAS:

  • PFOA (perfluorooctanoic acid), 
  • PFOS (perfluorooctane sulfonic acid), 
  • PFNA (perflouorononanoic acid), 
  • HFPO-DA or “GenX” (hexafluoroproplyene oxide dimer acid), 
  • PFHxS (perfluorohexane sulfonic acid), and
  • PFBS (perfluorobutane sulfonic acid). 

The proposed MCLs for these six PFAS as follows:  

Proposed: First Federal Limits on PFAS in Drinking Water

  • For PFOA, 4.0 parts-per-trillion 
  • For PFOS, 4.0 parts-per-trillion
  • For the other four PFAS, an MCL of 1.0*  

*The MCL of 1.0 is cumulative, based on a Hazard Index (HI) combining various risk factors.

The proposed rule also creates unenforceable health-based level of zero for PFOA and PFOS. 

About National Primary Drinking Water Regulation (NPDWR) 

The Safe Drinking Water Act authorizes US EPA to create National Primary Drinking Water Regulations (NPDWR). These regulations generally include limits on the concentration in drinking water of certain kinds of substances—microorganisms, organic and inorganic chemicals, disinfectants, and radionuclides. 

Public water systems or PWS (defined in 40 CFR 141.3) must notify customers via specified means whenever they detect a violation of a NPDWR. 

testing water for PFAS

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