In the March 3, 2021 Federal Register, EPA issued its final regulatory determinations for substances on the fourth Drinking Water Contaminant Candidate List (“CCL 4”). Under the federal Safe Drinking Water Act, EPA is required to publish a list every five years of chemicals that are known or suspected to be found in public drinking water systems and are not currently subject to EPA drinking water regulations. As part of the process, EPA must also select five or more contaminants from the CCL and determine whether or not to regulate them. These final regulatory determinations then factor into the six-year review process for EPA’s national primary drinking water regulations. For the CCL 4, EPA has made final determinations to regulate PFOA and PFOS in drinking water. The next step will be for EPA to develop national primary drinking water regulations for PFOA and PFOS, which will impose binding standards nationwide where currently only an advisory level exists (70 parts per trillion combined for PFOA and PFOS).

Separately but relatedly, the revised proposed fifth Unregulated Contaminant Monitoring Rule (“UCMR 5”) was published in the Federal Register on March 11, 2021 at Docket ID No. EPA-HQ-OW-2020-0530. UCMR 5, as proposed and revised, would require sample collection for 30 chemical contaminants – lithium and 29 PFAS chemicals – in drinking water between 2023 and 2025 using analytical methods developed by EPA and consensus organizations. The proposed action is intended to provide EPA, states, and communities with scientifically valid occurrence data on a national basis for these contaminants in drinking water – that is, how frequently the listed chemicals are found in drinking water systems and at what concentrations. The primary significance of the revisions to the proposed rule is the addition of 23 PFAS chemicals to the originally proposed six listed PFAS chemicals.

Viewed in combination, the two issuances are another step in EPA’s journey toward setting national binding regulatory levels for PFAS in drinking water. Further, the expansion of the UCMR to include a total of 29 PFAS substances may be indicative of an interest in exploring the possibility of future category-wide limits, as compared to individual limits on a smaller suite of PFAS compounds.

EPA is accepting public comments on the proposed UCMR 5 rule until May 10, 2021 at Docket ID No. EPA-HQ-OW-2020-0530 via the portal, or by mail or hand delivery. (Note that the published proposed rule states that comments on the information collection provisions of the proposed rule that are received on or before April 12, 2021, are “best assured of consideration.”) Moreover, EPA will hold two virtual public meetings via webinar to discuss the revised proposed rule, on April 6 and 7, 2021. Links to register for the webinars can be found here, where parties can also indicate their interest in offering a public statement of up to ten minutes in length (although formal comments must be submitted to the docket). EPA notes that capacity for the webinars is limited, so registration is first-come-first-served; additional webinars may be scheduled if stakeholder interest warrants.