EPA presents technical details of proposed PFAS drinking water rules


Mar. 29, 2023

On March 29, 2023, the Environmental Protection Agency’s Office of Water gave a presentation on the proposed per- and polyfluoroalkyl substances National Primary Drinking Water Regulation. The presentation focused on the technical aspects of the planned rule and what water systems could expect to deal with in the future.

Regulatory background

  • Per- and polyfluoroalkyl substances (PFAS) are a large class of synthetic chemicals first created in the 1940s and used in countless industrial, commercial, and residential uses since then. PFAS are well known for their ability to withstand heat and other environmental stressors, leading to their common nickname of “forever chemicals.” This resilience allows PFAS to persist in the environment and bioaccumulate in tissue.
  • The Environmental Protection Agency (EPA) first released Lifetime Health Advisories for two PFAS in 2016 and followed up with more health advisories in June 2022.
  • On March 29, 2023, the EPA officially proposed a National Primary Drinking Water Regulation (NPDWR) for six PFAS, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and hexafluoropropylene oxide dimer acid (HFPO-DA) (see an in-depth AgencyIQ analysis on the proposed rule here). The proposed regulations place individual maximum contaminant levels (MCL), or the maximum concentration a contaminant can be present, for PFOA and PFOS in drinking water. For the other four PFAS, the EPA used a Hazard Index for a combination of the substances in drinking water. The EPA also proposed health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs), which are the maximum level of a contaminant in drinking water where there are no known or anticipated negative health effects allowing for a margin of safety.

EPA presentation on PFAS

  • On March 29, 2023, the EPA’s Office of Water gave a technical presentation on many aspects of the rule. The agency began by explaining the process for formulating the rule, which began with evaluating what data was available and establishing the MCLG. These options were followed up by developing a health risk reduction and cost analysis to determine what are the impacts of policy alternatives to the rule and setting a standard (the MCLs and Hazard Index) as close as feasible to the MCLGs. The EPA finished the review with a cost-benefit analysis to determine the quantifiable costs and benefits of the rule, and what finalizing the rule will lead to.
  • The EPA noted that in determining the MCLGs, the agency determined that PFOA and PFOS are “likely to be carcinogenic to humans.” The EPA determined that PFOA was likely carcinogenic based on statistically significant evidence of kidney cancer in humans and Leydig cell tumors, pancreatic acinar cell tumors, and hepatocellular adenomas in rats. PFOS demonstrated statistically significant evidence of potentially human relevant tumors, including hepatocellular tumors in male and female rats and pancreatic islet cell tumors. The EPA therefore developed an MCLG of 0 for PFOA and PFOS as substances classified as “likely to be carcinogenic to humans” must have MCLGs of 0 where there is insufficient information to determine that a carcinogen has a threshold dose below which no carcinogenic effects have been observed.
  • The Agency explained that it considered the current proposed MCLs feasible as multiple approved EPA testing methods (namely 533 and 537.1) can reliably measure each of the six PFAS at or below the proposed MCL, and there are treatment technologies that can also treat and remove PFAS to below those MCLs.
  • The EPA also explained how the Hazard Index will be used. Hazard Indexes are used to evaluate potential health risks from contaminants and is based off a combination of the levels. Each individual PFAS within the Hazard Index has a specific concentration (ranging from 9 to 2000 ppt), which is then put into an equation to determine whether the total concentration of PFAS in the mixture violates the Hazard Index.
  • The presentation also touched on the monitoring requirements for public water systems under the proposed rule. Initial monitoring for water systems would have to be completed within the three years between the finalized rule’s publication date and the date the rule actually goes into effect. Based on these initial monitoring results, the EPA would require quarterly testing at most systems, but would also allow for monitoring flexibility to once or twice every three years for sampling locations where the result is below one third of the MCLs.
  • The agency utilized Practical Quantitation Levels (PQLs) for the six PFAS proposed for regulation, which is the “lowest concentration of a contaminant that can be reliably achieved within specified limits of precision and accuracy during routine laboratory operating conditions.” Under the proposed rule, the public would need to be notified by a water system of a violation within 30 days of detection as well as requiring community water systems to include PFAS information in the Consumer Confidence Report distribution to customers, such as the levels of regulated PFAS in the drinking water and the potential health effects of any regulated PFAS detections above the MCLs or Hazard Index.
  • The EPA also covered some of the more practical applications for treatment of PFAS in water systems. Among PFAS treatment methods, granular activated carbon (GAC), anion exchange (AIX), and nanofiltration (NF) and reverse osmosis (RO) technologies are the most effective at treating and removing PFAS (and other contaminants) from the water supply. Each of these technologies can treat and remove PFAS below the analytical detection limit, according to the EPA. The EPA noted that longer chain PFAS (such as PFOA and PFOS) are easier to remove than shorter chain PFAS, likely due to the smaller molecules being harder to strain or remove from water.
  • In terms of costs and benefits, the EPA currently expects that the benefits (both quantifiable and unquantifiable) will outweigh the costs of the rule. The agency also explained how the Bipartisan Infrastructure Law provides funding for water systems to invest in PFAS treatment and removal technologies, with two separate funds totaling $9 billion, with an additional $12 billion in loans for general investments in drinking water safety.

Next steps

  • The Agency noted that many states may have different requirements than the EPA for PFAS in drinking water. The agency explained that at this time, all water systems should follow state requirements, but that as of the rule’s effective date, the nationwide standard will change to the EPA’s creation of a regulatory “floor” which states may build from but not go below.
  • The EPA expects the proposed rule to be finalized in December 2023. This would mean that the actual effective date for the rule would be in late 2026.
  • The EPA is accepting comments on the PFAS NPDWR until May 30, 2023. Comments may be submitted through the regulations.gov portal linked here.

To contact the author of this analysis, please email Walker Livingston.
To contact the editor of this analysis, please email Patricia Iscaro.

Key Documents and Dates

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