The U.S. Environmental Protection Agency (EPA) has released the first dataset collected under the fifth Unregulated Contaminant Monitoring Rule (UCMR 5), which is intended to provide new information that will improve EPA’s understanding of the frequency that 29 per- and polyfluouralkyl substances (PFAS) and lithium are found in U.S. drinking water systems, and at what levels. The monitoring data on PFAS and lithium will help the EPA make determinations about future actions to protect public health under the Safe Drinking Water Act.

The data collected under UCMR 5 will ensure science-based decision-making and help EPA better understand national-level exposure to 29 PFAS and lithium, and whether they disproportionately impact communities with environmental justice concerns. The initial data release represents approximately 7 percent of the total results that EPA expects to receive over the next three years. The agency will update results quarterly and share them with the public in EPA’s National Contaminant Occurrence Database (NCOD) until completion of data reporting in 2026.

In March 2023, EPA proposed standards to limit certain PFAS in drinking water. The proposal, if finalized, would allow public water systems to use results from UCMR 5 to meet the rule’s initial monitoring requirements and to inform communities of actions that may need to be taken. In the interim period before the PFAS drinking water standard is final, EPA has established Health Advisories (HAs) for four PFAS included in the UCMR 5.

Based on the limited initial set of data, EPA concluded:

• PFOA and PFOS are two of the most widely studied PFAS. One or each of these two PFAS was measured at or above EPA’s minimum reporting level (MRL), and therefore above EPA’s HA levels, in the first sampling event for 7.8–8.5 percent of public water systems (PWSs) with results to date.
• The other two PFAS with EPA HA levels are HFPO-DA (also known as “GenX chemicals”) and PFBS. HFPO-DA was measured above the HA level in 1 of 2,002 PWSs. PFBS was not found above the HA level.
• HA levels have not been established for the other 25 PFAS that are part of UCMR 5. Nine of these 25 PFAS were measured at or above their respective MRL in 1–207 of approximately 2,000 PWSs. For the other 16 PFAS, no PWSs have reported results at or above their respective MRLs.
• EPA has not published a HA level for lithium but has calculated a Health Reference Level (HRL) for screening purposes. To date, 22 percent of PWSs have reported lithium results above the screening HRL.

EPA is moving forward to expand the investigation and cleanup of PFAS contaminated sites, including by finalizing new safeguards to hold polluters accountable for contamination from two widely used PFAS chemicals. The agency also recently issued its third order to require PFAS manufacturers to conduct testing under EPA’s National Testing Strategy to help EPA better confront PFAS.

EPA is also deploying $9 billion to invest in communities with drinking water impacted by PFAS and other emerging contaminants, including $4 billion via the Drinking Water State Revolving Fund (DWSRF) and $5 billion through EPA’s “Emerging Contaminants in Small or Disadvantaged Communities” grant program. The funds will help communities make investments in solutions to remove PFAS from drinking water.