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Regulatory Updates

Fifth Unregulated Contaminant Monitoring Rule Lists 29 PFAS

January 21, 2022

The U.S. Environmental Protection Agency (EPA) published the fifth Unregulated Contaminant Monitoring Rule (UCMR5), on December 27, 2021, requiring the sample collection for 30 chemical contaminants from public water systems (PWSs) between 2023 and 2025. Under the Safe Drinking Water Act (SDWA), the EPA is required to issue a list of unregulated contaminants once every five years that will be monitored by PWSs. Out of the 30 contaminants, 29 are per-and polyfluoroalkyl substances (PFAS) that have validated laboratory analytical methods (Methods 533 and 537.1) and are not currently subject to a national primary drinking water regulation, with the remaining constituent, lithium (Table 1 below).

The planned monitoring will occur over a 12-month period between January 2023 and December 2025.

The EPA will fund the monitoring activities and is responsible for all analytical costs associated with monitoring of systems serving 10,000 or fewer people. All samples will be collected from the entry points to the distribution systems.

The purpose of the UCRM5 program is to collect scientifically valid data to better understand the national occurrence (frequency and magnitude) of these unregulated contaminants in drinking water. The collection of these data will help guide science-based decision-making and prioritization of disadvantaged and affected communities.

As part of the EPA’s PFAS Strategic Roadmap, the UCMR5 program will also help focus efforts and attention on those PFAS that are more prevalent throughout the country and will draw attention to elevated areas of concern. The results of the UCMR5 may also help inform regulatory and risk management decisions. Additionally, the data may highlight PWSs in need of infrastructure funding for advanced emerging contaminant remediation. The UCMR5 may also impact various clients who are in the vicinity of PWSs that report elevated PFAS concentrations by increasing public scrutiny, and potentially being subjected to required testing.

Contact Elizabeth Denly at or Emily Larson at for help in preparing proactively for regulatory and risk management decisions that might be necessitated from this UCMR5 program.

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