Earlier this week, the U.S. Environmental Protection Agency issued a Notice of Proposed Rulemaking titled, PFAS National Primary Drinking Water Regulation Rulemaking.
In keeping to its commitments in the PFAS Strategic Roadmap, the EPA took a significant step by proposing to establish legally enforceable drinking-water levels for six per- and polyfluoroalkyl substances (PFAS) known to occur in drinking water: PFOA, PFOS, PFHxS, GenX Chemicals, PFNA, and PFBS.
“Through this proposed rule, EPA is leveraging the most recent science and building on existing state efforts to limit PFAS, and provide a nationwide, health-protective standard for these specific PFAS in drinking water.”
Under the Safe Drinking Water Act (SDWA), EPA has the authority to set enforceable National Primary Drinking Water Regulations (NPDWRs) for drinking-water contaminants and require monitoring of public water supplies. EPA initiated the process for developing a NPDWR for PFAS compounds in March 2021, when EPA published the fourth regulatory determinations for contaminants on the fourth Contaminant Candidate List, which included a final determination to regulate PFOA and PFOS in drinking water.
The EPA proposes to set individual Maximum Contaminant Levels (“MCLs”) of four parts per trillion for PFOS and PFOA. According to EPA, this is “the lowest feasible level based on the ability to reliably measure and remove these contaminants from drinking water.”
An MCL is an enforceable regulatory level for public drinking water systems established as close as is feasible to the Maximum Contaminant Level Goal (“MCLG”), taking costs into consideration. See 42 U.S.C. § 300g–1(b)(4)(B). EPA proposes to set the MCLG at zero for these two substances. “EPA’s proposed rule is informed by regulatory development requirements under the [SDWA], including EPA’s analysis of the best available and most recent peer reviewed science.” The proposal also takes into account the feasibility of analysis and treatment, as well as consideration of costs and benefits. That economic analysis can be found here.
In addition to its proposed MCLs for PFOA and PFOS, EPA proposed a Hazard Index for PFHxS, GenX Chemicals, PFNA, and PFBS. In proposing this hazard index, EPA stated that it “is following recent peer-reviewed science that indicates that mixtures of PFAS can pose a health risk greater than each chemical on its own.”
“A Hazard Index helps to account for the increased risk from mixtures of PFAS that may be found in contaminated drinking water.” The Hazard Index “considers how toxic each of the four PFAS are and allows a site-specific determination based on the specific drinking water concentrations.” EPA did not include PFOA and PFOS in the hazard index MCL because it determined that “PFOA and PFOS are likely carcinogens (i.e., cancer causing) and that there is no level of these contaminants that is without a risk of adverse health effects.”
EPA’s proposed rule would require that all community water systems and non-transient, non-community water systems conduct initial monitoring within three years after the rule’s promulgation. Based on their size and source water, systems would have to conduct initial monitoring either twice, or quarterly, during a 12-month period as follows:
- Groundwater systems serving greater than 10,000 customers would initially be required to monitor quarterly within a 12-month period;
- Groundwater systems serving under 10,000 customers would initially be required to only monitor twice within a 12-month period, with each sample 90 days apart.
- Surface water systems would initially be required to monitor quarterly within a 12-month period.
To help reduce costs, systems would be allowed to use previously collected monitoring data to satisfy the initial monitoring requirements if the sampling was conducted using EPA Methods 533 or 537.1 as part of UCMR 5 or pursuant to other state-level or other appropriate monitoring campaigns.
If put into law, these water systems may be required to “install water treatment or consider other options such as using a new uncontaminated source water or connecting to an uncontaminated water system.” Activated carbon, anion exchange and high-pressure membrane technologies have all been demonstrated to remove PFAS from drinking water systems. But at this time, EPA recommends that communities and water systems “follow applicable state requirements, recognizing that EPA’s proposed rule does not currently require water systems to take any action.”
If the final NPDWR goes into effect, states will then be required to have a standard that is no less strict than the NPDWR in accordance with the requirements of the SDWA.
The proposed rules will be open for public comment for 60 days after publication of the notice in the Federal Register, which has not yet occurred.