This week the U.S. Environmental Protection Agency (EPA) scheduled two webinars on implementation of the ongoing Unregulated Contaminants Monitoring Rule Monitoring (UCMR5). All systems that serve more than 3,300 persons should be prepared to implement UCMR5 monitoring. Note: If you with a system serving more than 3,300 persons and are not familiar with UCMR5, please review the materials available here . All systems serving more than 10,000 persons should have their monitoring plans submitted and be prepared to conduct sampling. EPA outlined its approach for communicating UCMR5 results in webinars this week. The webinar slides are available here . EPA made several points that water systems should keep in mind as they plan for how they will communicate with their customers about observed per- and polyfluoroalkyl substances (PFAS) and lithium in their monitoring results, including: EPA will distribute preliminary UCMR5 data for small systems first to the agency Regions, which will share data with states. Systems with values above health advisories will receive notification from states. Starting mid‐2023, EPA will update the National Contaminant Occurrence Database (NCOD) with UCMR5 results and publish a “Data Summary” approximately quarterly at https://www.epa.gov/dwucmr/occurrence‐data‐unregulated‐contaminant‐monitoring‐rule . Health‐based reference values, or “HBRVs” (i.e., reference concentrations) do not represent regulatory limits or action levels and should not be interpreted as an indication of future EPA actions. EPA frames its knowledge of health effects for unregulated contaminants as incomplete. (Note: This uncertainty may signal to some people that the analyte may be riskier than the HBRVs suggest). Health advisories are available for lithium and all four PFAS required under UCMR5 monitoring. Agency for Toxic Substances and Disease Registry (ATSDR) minimum risk levels are available for two PFAS. The reference dose only -- the dose used to calculate a health-based reference concentration -- is available for one PFAS. See https://www.epa.gov/system/files/documents/2023-02/UCMR5-HBRV.pdf . HBRVs may change during UCMR5 (Note: EPA is proposing maximum level of contamination goals (MCLGs) for at least two PFAS shortly; two draft health risk assessments were identified. Health advisories are non‐enforceable and non‐regulatory. Lifetime health advisories are designed to protect all people, including sensitive populations and through all life stages, from adverse health effects resulting from exposure throughout their lives to contaminants in drinking water. Health advisories are calculated to offer a margin of protection against adverse health effects They take into account other potential sources of exposure (e.g., food, air, consumer products). They establish levels at or below which no adverse effects are expected. The lithium health reference level is “is based on adverse health effects at therapeutic doses which are much higher than estimated average intake from drinking water or dietary sources.” States may have their own advisory levels or regulations for PFAS. Community water systems are responsible for being aware of and complying with their State’s requirements. Minimum reporting limits (MRLs) are not associated with contaminant health effects information. The UCMR is an integral component of the Safe Drinking Water Act (SDWA) regulatory setting process, and water systems should prepare now to implement the rule. Importantly, in finalizing UCMR5, EPA anticipates that all public water systems serving 3,300 persons or more will be required to conduct sampling under the rule. This expands the number of systems serving between 3,300 and 10,000 persons that will conduct monitoring. There will be a statistical sample of 800 smaller systems as well. This expanded sampling plan is contingent on EPA receiving adequate funding to support sample analysis for systems serving less than 10,001 persons. Because EPA will bear the UCMR5 analytical costs for small systems and federal appropriations can be uncertain each year, EPA is using a “monitor if notified” approach for systems serving 25 to 10,000 people. By early 2023, EPA will notify all small systems serving between 3,300 and 10,000 people of their anticipated requirement to monitor; EPA expects to confirm and schedule monitoring by July 1 preceding each collection year based on the availability of appropriations. NOTE: UCMR is implemented directly by EPA. States provide some assistance to EPA. Systems may receive less direction and assistance from states than if the state primacy agency was responsible for implementation. UCMR5 includes monitoring (1) 29 per- and polyfluoroalkyl substances (PFAS) using both EPA Method 533 and EPA Method 537.1 and (2) lithium using one of several identified methods. PFAS and lithium are topics that may require a focused communication effort. Systems will schedule required sampling events within the January 2023 – December 2025 sampling period in coordination with EPA. AWWA has a suite of resources available on its PFAS resource page , including: AWWA Connections article on UCMR5 AWWA Briefing on PFAS PFAS Technical Report Set , including a “ Source Water Evaluation Guide for PFAS ” Lithium in Drinking Water Trending in an Instant: A Risk Communication Guide for Water Utilities AWWA recommends members review the posted data and post local results on their websites to demonstrate transparency, explain the purpose of UCMR and properly characterize results. Questions can be directed to Steve Via , AWWA’s federal relations director, or Greg Kail , AWWA communications director.