In July 2023, the Environmental Protection Agency (US EPA) released the first set of data collected under the fifth Unregulated Contaminant Monitoring Rule (UCMR5). The list of contaminants being monitored in drinking water under UCMR5 include 29 per- and polyfluoroalkyl substances (PFAS) and lithium.

• PFOA was detected at or above the US EPA’s minimum reporting level (MRL) at 156 public water systems (PWSs), representing 7.8% of the PWSs with results. PFOS was detected at or above the MRL at 170 PWSs, representing 8.5% of the PWSs with results. PFOA and PFOS both have established health advisories (HAs) below their respective MRLs, so all positive results reported for PFOA and PFOS exceeded their HA levels.
• PFBS was not detected above its HA level, and HFPO-DA was detected above its HA level by only one of the more than 2000 PWSs reporting results.
• PFBA, PFHxA, and PFPeA were detected at or above their respective MRLs at 9.9-10.3% of PWSs reporting results. HAs have not yet been established for these PFAS.
• There are 16 PFAS covered under UCMR5 which were not detected at any PWS reporting results. HAs have not yet been established for those PFAS.

The data reported so far represent less than 10% of the total results expected under UCMR5, and the US EPA expects to update the results quarterly as more data are collected over the next 3 years. For  more information on UCMR5 visit the UCMR5 website, and to review the data sorted by state or analytical method visit Occurrence Data (July 2023)