On December 20, 2021, U.S. EPA finalized its Fifth Unregulated Contaminant Monitoring Rule (UCMR) that will require public water systems (PWS) to collect monitoring data for 29 per- and polyfluoroalkyl substances (PFAS) and lithium in drinking water. Every five years, the Safe Drinking Water Act (SDWA) requires U.S. EPA to publish a new list of unregulated contaminants that will be monitored by PWS. UCMR 5 focuses almost exclusively on PFAS and targets 29 of the more than 4,700 PFAS that have been identified to date.
Starting in 2023, all PWSs serving more than 10,000 customers are obligated to monitor for these UCMR 5 contaminants while smaller PWSs (those serving less than 10,000 customers) must monitor subject to availability of appropriations (U.S. EPA is responsible for all analytical costs associated with PWSs serving less than 10,000 customers) and laboratory capacity. In response to comments on the draft UCMR 5 expressing concern about the lack of laboratory capacity to support the PFAS monitoring, the final rule notes that U.S. EPA expects laboratory capacity to quickly grow to meet UCMR demand. The final rule identifies applicable U.S. EPA test methods for each of the 29 targeted PFAS compounds. However, some commenters were critical that the final rule did not identify a testing technique to determine "total PFAS" in drinking water. The final rule acknowledges this issue but notes that U.S. EPA "has not identified a complete, validated peer-reviewed aggregate PFAS method" at this time.
The data collected is expected to inform U.S. EPA as it evaluates whether to set a specific drinking water limit or treatment standard under the SDWA for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). U.S. EPA has committed to establishing a national drinking water regulation for PFOA and PFOS by the fall of 2023 and it is likely that additional PFAS will be in the SDWA regulatory pipeline in the near future.
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