On March 14, EPA released a proposed rule establishing national drinking water standards for PFAS. The proposed rule is part of the Agency’s PFAS Strategic Roadmap. It seeks to regulate PFOA and PFOS as individual contaminants and four additional PFAS (PFNA, PFHxS, PFBS, and GenX chemicals) as mixtures. EPA intends to regulate PFOA and PFOS at the lowest level of which they can be reliably measured, which the Agency has determined to be 4 parts per trillion.
For the additional four PFAS, EPA proposed maximum concentration limits (MCLs) for any mixture containing one or more of these substances. This would require water systems to use an approach called Hazard Index Calculation to determine if the combined levels of these PFAS pose a potential risk. Hazard Indexing is a tool used to evaluate the health risks of simultaneous exposure to mixtures of related chemicals. To determine the Hazard Index for these four PFAS, water systems would be required to monitor drinking water and compare the amount of each PFAS in the water to its associated Health-Based Water Concentration (HBWC). HBWCs are the levels at which no health effects are expected.
In remarks accompanying the Agency’s press release on the proposed rule, Administrator Michael S. Regan commented, “EPA’s proposal to establish a national standard for PFAS in drinking water is informed by the best available science and would help provide states with the guidance they need to make decisions that best protect their communities. This action has the potential to prevent tens of thousands of PFAS-related illnesses and marks a major step toward safeguarding all our communities from these dangerous contaminants.”
The proposed rule is causing great concern in the wastewater utility and chemicals industries. They are apprehensive about the logistical and financial hurdles that implementing the rule would entail. Both the American Chemistry Council and the National Association of Water Companies, a trade group representing investor-owned utilities, have voiced concerns, claiming that compliance with the rule will cost billions of dollars. The Agency is actively working with financial institutions to help utilities in vulnerable communities with limited resources comply with the rule and claims $9 billion is already earmarked for this purpose from bills approved by Congress since 2021.
Additional information can be found in EPA’s Proposal to Limit PFAS in Drinking Water Fact Sheet.