Unregulated Contaminant Monitoring Rule 5 (UCMR 5)

Western Water is participating in the U.S. Environmental Protection Agency’s (EPA) fifth round of the Unregulated Contaminant Monitoring Rule (UCMR 5).

What is the Unregulated Contaminant Monitoring Rule (UCMR 5)?

 The Safe Drinking Water Act (SDWA) requires the EPA to establish criteria for a program to monitor unregulated contaminants in drinking water and to identify contaminants to be monitored every five years. The UCMR dataset is one of the primary sources of information on the occurrence and population exposure that the EPA uses to develop regulatory decisions for contaminants in the public drinking water supply. 

Under UCMR 5, 10,311 utilities nationwide will monitor unregulated contaminants for one year to help the EPA determine the occurrence of these contaminants in drinking water and whether or not they need to be regulated for the protection of public health.

Click here to learn more about the Fifth Unregulated Contaminant Monitoring Rule.

How is Western Water participating?

As part of the UCMR 5 program, Western Water began collecting samples quarterly in 2023. The samples that have been and will continue to be collected represent the various sources of finished water supplied to our customers. Under UCMR 5, Western Water was required to collect drinking water samples for 29 per- and polyfluoroalkyl substances (PFAS) and lithium. This data will help to improve the EPA’s understanding of the frequency that 29 PFAS (and lithium) are found in the nation’s drinking water systems and at what levels.  

Click here to view all national data collected under UCMR 5 for 29 PFAS and lithium.

Western Water is committed to protecting public health and will continue to monitor and support the EPA’s research on these contaminants. 

Review the latest Western Water UCMR 5 test results.