The Importance of UCMR Testing

Every five years, the U.S. Environmental Protection Agency (EPA) implements the Unregulated Contaminant Monitoring Rule (UCMR). The purpose of UCMR is to collect data from utilities like ours about contaminants that may be present in drinking water. The EPA uses this data to decide if specific contaminants occur at frequencies and concentrations high enough to be regulated in the future.

Trace amounts of naturally occurring or man-made substances can sometimes find their way into drinking water supplies, and not all are currently regulated by EPA. Today’s advanced analytical methods can detect contaminants at trace levels, but the presence of trace levels does not necessarily pose a safety concern.                

UCMR testing is part of the federal Safe Drinking Water Act.

UCMR5 Testing

Five of the City of Houston's systems are participating in the EPA’s fifth round of UCMR testing, known as UCMR5, which requires us to monitor for 30 chemical contaminants using analytical methods approved by EPA. It can be a lengthy process to set drinking water regulations, but it is important that EPA completes its thorough, scientific process to fully understand the potential health impacts, maximum contaminant levels, analytical methods, and treatment methods to provide public utilities with proven, consistent standards.                

The contaminants we are testing include 29 per- and polyfluoroalkyl substances (known as PFAS) and lithium. Testing will take place during the 2023, 2024 and 2025 calendar years. Updated results will be posted on a quarterly basis as they become available. For more information on PFAS, click here.                

On April 10, 2024, EPA announced the final National Primary Drinking Water Regulation (NPDWR) for six PFAS. EPA established legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water: PFOA, PFOS, PFHxS, PFNA, and HFPO-DA as contaminants with individual MCLs, and PFAS mixtures containing at least two or more of PFHxS, PFNA, HFPO-DA, and PFBS using a Hazard Index MCL to account for the combined and co-occurring levels of these PFAS in drinking water. EPA also finalized health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these PFAS.

The final rule requires:  

• Public water systems must monitor for these PFAS and have three years to complete initial monitoring (by 2027), followed by ongoing compliance monitoring. Water systems must also provide the public with information on the levels of these PFAS in their drinking water beginning in 2027. 
• Public water systems have five years (by 2029) to implement solutions that reduce these PFAS if monitoring shows that drinking water levels exceed these MCLs. 
• Beginning in five years (2029), public water systems that have PFAS in drinking water which violates one or more of these MCLs must take action to reduce levels of these PFAS in their drinking water and must provide notification to the public of the violation. 

If you would like more information on the EPA’s Unregulated Contaminants Monitoring Rule (UCMR), please call the federal Safe Drinking Water Hotline at (800) 426-4791.             
For more information about Houston's test results, call 832-395-3113 or email [email protected].  

VIEW & DOWNLOAD TEST RESULTS FROM THE                
PREVIOUS UCMR5 SAMPLING EVENTS

UCMR 5 Sampling Results (Entry Point to Distribution)

Click here to see detailed results for the Main System PWS1010013 - Samples scheduled for February, May, August, and November 2023  
Click here to see detailed results for the Kingwood System PWS1010348 - Samples scheduled for June and December 2023  
Click here to see detailed results for the Willow Chase System PWS1011902 - Samples scheduled for January and July 2024  
Click here to see detailed results for the District 73 System PWS1011585 - Samples scheduled for June and December 2024  
Click here to see detailed results for the District 82 System PWS1011593 - Samples schedule for February and August 2024

For additional information on UCMR 5 go to: https://www.epa.gov/dwucmr