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Unregulated Contaminant Monitoring Rule (UCMR)

  Water Info / What's in My Water? / Unregulated Contaminant Monitoring Rule (UCMR)

Egyptians drinking water

 

What is the UCMR?

Under the 1996 amendments to the federal Safe Drinking Water Act, the U.S. Environmental Protection Agency is required once every five years to issue a new list of up to 30 unregulated contaminants for which public water systems must monitor. The intent of this rule is to provide baseline occurrence data that the EPA can combine with toxicological research to make decisions about potential future drinking water regulations.

The current UCMR, the Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), was published Dec. 27, 2021. The EPA, the states, laboratories and public water systems will participate in the testing for UCMR 5 in various ways. The testing began in January 2023  and will continue through December 2025.

The contaminants monitored under UCMR 5 include:
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS) perfluorododecanoic acid (PFDoA).
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS) perfluoroheptanesulfonic acid (PFHpS).
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS) perfluoroheptanoic acid (PFHpA).
4,8-dioxa-3H-perfluorononanoic acid (ADONA) perfluorohexanesulfonic acid (PFHxS).
9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) perfluorohexanoic acid (PFHxA).
hexafluoropropylene oxide dimer acid (HFPO–DA) (GenX) perfluorononanoic acid (PFNA).
nonafluoro-3,6-dioxaheptanoic acid (NFDHA) perfluorooctanesulfonic acid (PFOS).
perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) perfluorooctanoic acid (PFOA).
perfluoro-3-methoxypropanoic acid (PFMPA) perfluoropentanesulfonic acid (PFPeS).
perfluoro-4-methoxybutanoic acid (PFMBA) perfluoropentanoic acid (PFPeA).
perfluorobutanesulfonic acid (PFBS) perfluoroundecanoic acid (PFUnA).
perfluorobutanoic acid (PFBA)  
Four Per- and Polyfluoroalkyl Substances (PFAS) using EPA Method 537.1 (SPE LC/MS/MS): 2  
n-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) perfluorotetradecanoic acid (PFTA).
n-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) perfluorotridecanoic acid (PFTrDA).
Lithium  

There are more than 10,000 water systems participating in UCMR 5. It is likely that your water provider is participating in UCMR testing in some capacity. Monitoring required by UCMR 5 is expected to require monitoring for all public water system all public water systems serving more than 3,300 people to participate in the testing with 800 systems serving as a representative sample for smaller systems. The testing began in January 2023 and will continue through December 2025. You can contact your local water provider to ask about its participation in UCMR testing.

The test results are used to help determine whether certain contaminants are found in drinking water, at what levels they are found, and in which parts of the country.

Depending on how prevalent the contaminants are and at what levels they are found, EPA may conduct an evaluation to determine whether to begin regulating some or all of them.

In many cases, utilities will be testing for these contaminants at very low levels. That does not mean those contaminants have been determined to be harmful at those levels. EPA sets these testing levels based on the capabilities of current analytical methods and the agency's need to identify reference concentrations, so that they can offer context when they are making health-based regulatory decisions.