On March 14, 2023, the United States Environmental Protection Agency (EPA) announced its proposed National Primary Drinking Water Regulation (NPDWR), which would establish legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water. These PFAS chemicals are:
EPA described the proposed MCL of 4 ppt for PFOA and PFOS to be the “lowest feasible level” for which PFOA and PFOS can reliability be measured and removed from drinking water. EPA has also proposed using a “Hazard Index” score as an MCL for a combination of four PFAS compounds - PFHxS, GenX chemicals, PFNA and PFBS. This is the first time that a hazard index approach is being proposed as a federal drinking water MCL standard. In short, a Hazard Index considers how toxic each of the four PFAS are and then uses a site-specific determination based on the specific drinking water concentrations (i.e., the calculation gets complicated).
Maximum Contaminant Level Goals (MCLGs)
EPA is also proposing health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these six PFAS. An MCLG is the level of a contaminant in drinking water at which EPA has determined no known or anticipated negative health effects occur and which allows an adequate margin of safety. The proposed MCLG for PFOA and PFOS is zero, and the MCLG for the other four PFAS compounds is the same as the MCL - a Hazard Index score of 1.0. While not enforceable, MCLGs could be referenced in future regulatory efforts at both federal and state levels.
What the Proposed Rule Would Require
The proposed rule would require all community water systems and non-transient, non-community water systems to conduct initial monitoring within 3 years after the rule’s promulgation. Depending on size and source water, systems must conduct initial monitoring either twice or quarterly during a 12-month period. In addition to monitoring, the proposed rule would require public water systems to notify the public of the levels of these six PFAS and reduce the levels of these same chemicals in drinking water if they exceed the proposed MCL standards.
Timing and Public Comment Period
The proposed PFAS NPDWR does not require any actions until it is finalized. As per the Safe Drinking Water Act (SDWA), EPA is required to promulgate a final rule within 18 months after the proposed rule. EPA anticipates finalizing the regulation by the end of 2023.
When the proposed rule is published in the Federal Register there will be a 60-day public comment period. We expect to see comments and potential challenges to the rule regarding the estimated/proposed costs of implementation, EPA’s decision to make preliminary regulatory determinations for PFHxS, PFNA, PFBS and GenX within the context of the proposed rule, and EPA’s scientific justification regarding the proposed MCLs and use of the Hazard Index approach to set MCLs.
Impact on State MCLs
Although many states have already established MCLs or similar restrictions on PFAS in drinking water, no state has promulgated an MCL as low as EPA’s proposed 4 ppt for PFOA and PFOS. Therefore, when finalized, the SDWA requires states to promulgate MCLs that have a standard at least as stringent as the final NPDWR. The process for getting federal MCLs through a state rulemaking process would be covered by each state’s administrative process. For example, it is expected that EPA’s MCLs will not take effect in Wisconsin until three years after a federal MCL is finalized.
Are you Prepared?
This action is included in EPA’s “PFAS Strategic Roadmap” announced in October 2021. Michael Best will continue to track rulemaking, funding, and other PFAS regulatory efforts at EPA and beyond. The environmental team at Michael Best has experience advising clients on PFAS-related issues. If you have any questions or concerns about how EPA’s proposed drinking water regulations may impact your facility, please contact your Michael Best attorney or any of the authors listed here.