The U.S. Environmental Protection Agency (USEPA) recently published its ninth set of national drinking water data collected under the fifth Unregulated Contaminant Monitoring Rule (UCMR 5). The UCMR 5 requires sample collection for 30 chemical contaminants between 2023 and 2025. The collected data helps measure the amount of lithium in the nation’s drinking water as well as 29 per- and polyfluoroalkyl substances (PFAS).
Tim Stefanich, PE, AE2S Senior Advanced Technical Specialist reviewed the lithium data for 10 states and organized the information into three tables, including groundwater results, surface water results, and combined data for groundwater and surface water systems. For categorical purposes, Stefanich assumed mixed sources as surface water and groundwater under the influence of surface water as ground water.
“There is currently no Health Advisory Level (HAL) for Lithium, only a Health Reference Level (HRL) of 10 µg/L. HALs are a non-regulatory concentration at which no adverse health effects or aesthetic effects are anticipated. HRLs are risk-based concentrations used by USEPA to evaluate if a contaminant occurs at levels of concern in drinking water,” explains Stefanich. “Once EPA reviews the UCMR5 occurrence data across the country, and additional health effects data is received, then it will be determined if lithium will be regulated, and if so, at what concentration.”
The Water Research Foundation currently has two studies underway related to treating lithium in drinking water. The Lithium Treatment Strategies in Drinking Water study (Project 5268) began in August 2024 and is scheduled to be complete in 2027, while the Treatment Strategies for the Removal of Lithium from Drinking Water study (Project 5258) began in September 2023 and is scheduled to wrap up in 2026.
USEPA uses the UCMR to collect data for contaminants that are suspected of being present in drinking water and do not yet have regulatory standards set under the Safe Drinking Water Act (SDWA). The Safe Drinking Water Act (SDWA) requires USEPA to issue a list of unregulated contaminants once every five years to be monitored by public water systems. The monitoring provides nationally representative data on the occurrence of contaminants in drinking water, the number of people potentially being exposed, and an estimate of the levels of that exposure. The data is utilized to make regulatory determinations to protect public health.
If you would like to dig deeper in the UCMR 5 data release,check out these USEPA resources:
- UCMR 5 Data Finder – UCMR 5 results can be easily located, viewed, and summarized as well as downloaded.
- Occurrence Data Text Files –The files contain analytical results and the additional data element and ZIP Code information reported by participating public water systems.
- UCMR 5 Data Summary – National summary statistics by contaminant, health effects information, data considerations, and data definitions for the UCMR 5 Data Finder and Occurrence Data Text Files.
- UCMR 5 Q&A – Answers to common questions on accessing and understanding the UCMR 5 data, and on PFAS and lithium in drinking water.
Reach out to Nate Weisenburger, AE2S Drinking Water Practice Leader, if you have questions about the UCMR 5.