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3/17/2025
WT Staff
 Got water questions? Give us a call at 877-52-WATER (877-529-2837), or email us at info@wtla.us
March 17, 2025 345 pm CDT
Some do, some don't - State drinking water regulations vs Safe Drinking Water Act and the EPA Unregulated Contaminant Monitoring Rule
Wondering why drinking water regulations vary from State to State? It has something to do with the US EPA Unregulated Contaminant Monitoring Rule (UCMR). New or emerging contaminants of concern are proposed for assessment to determine whether or not they need to be added to the US EPA Safe Drinking Water Act.
"UCMR provides EPA and others with scientifically valid data on the occurrence of these contaminants in drinking water. This permits assessment of the population being exposed and the levels of exposure."
New contaminants added to the National Primary Drinking Water Regulations come with a
legally enforceable limit binding on all licensed public drinking water facilities in the USA. Once a contaminant becomes part of the law, a grace period applies, allowing facilities to set up to meet the new requirement, up to five years depending on the cost and complexity of the upgrade.
See prior article on the latest changes to the SDWA, regulation of six PFAS compounds in drinking water, here.
How does a contaminant become part of the US EPA Safe Drinking Water Act?
In each new cycle, new contaminants are proposed for assessment, with a period of public notice and input. The first cycle was launched in 1999, the fifth cycle of testing will conclude testing in December 2025 with the law already announced April 2024 to regulate six specific PFAS compounds. The sixth cycle is in the late planning stage. Each cycle can run up to five years before a determination is made to regulate or not to regulate.
In the event that the contaminant does not become part of the SDWA, the US EPA may issue a Health Guidance document advising a concentration considered acceptable for public exposure. States may adopt a more careful health guidance. For example, the US EPA determined that cyanotoxins, the harmful compounds released by bluegreen algae are not of widespread occurrence resulting in significant national exposure through drinking water to warrant inclusion in the SDWA. California and Ohio went ahead and adopted more stringent positions on cyanotoxins, requiring routine monitoring by the drinking water facilities, including compliance with an established MCL for at least one cyanotoxin in drinking water. California Health went further, adopting a much lower MCL than the US EPA Health Guidance for specific cyanotoxins in both drinking water and recreational water, an order of magnitude more stringent than the federal EPA.
See California vs US EPA health guidance on cyanotoxins, here.
Unregulated Contaminant Monitoring Cycles
Careful assessment of contaminants not already regulated under the SDWA is carried out across all drinking water facilities serving more than 3300 population in the USA, with random sampling of the smaller facilities. Facilities with more than ten thousand residents pay the cost of the UCMR testing, US EPA covers the cost of lab analysis for the smaller facilities.
- UCMR 1 was published in the Federal Register on September 17, 1999. It required monitoring for 26 contaminants including propellants, fuel additives and pesticides.
- UCMR 2 was published in the Federal Register on January 4, 2007. It required monitoring for 25 contaminants, including flame retardants, pesticides, explosives and disinfection by-products.
- UCMR 3 was published in the Federal Register on May 2, 2012. It required monitoring for 30 contaminants including metals, PFAS, hormones and solvents.
- UCMR 4 was published in the Federal Register on December 20, 2016. It required monitoring for 30 chemical contaminants including metals, pesticides, cyanotoxins and disinfection by-products.
- UCMR 5 was published in the Federal Register on December 27, 2021. It requires monitoring for 29 per- and polyfluoroalkyl substances (PFAS) and lithium with sample collection from January 2023 through December 2025 .
- UCMR 6 Pre-proposal phase - The EPA hosted two webinars in April 2024 to discuss potential approaches for developing UCMR 6, including: the status of drinking water analytical methods and contaminants being considered; possible sampling design; laboratory approval; other potential aspects of the monitoring approach; and included time for public questions and statements. The roster of contaminants for UCMR 6 is pending, more to follow.
According to the US EPA, "UCMR data represent one of the primary sources of national occurrence data in drinking water that EPA uses to inform regulatory and other risk management decisions for drinking water contaminants. This data will ensure science-based decision-making and help prioritize protection of disadvantaged communities."
Note that consideration is given to feasibility in determination whether or not to regulate a contaminant within the law. If it is not reasonable for drinking water facilities to achieve a set contaminant level, the contaminant may not be added to nation wide regulations. Consider the need for continuous technology development to keep pace with emerging contaminant threats. Even when new technology is developed on the lab bench, it may not be feasible at industrial scale.
See an article on emerging technology for drinking water treatment facilities to separate and destroy PFAS, here.
The Safe Drinking Water Act protects public health through the administration and delivery of quality drinking water supplies across the USA. The US EPA establishes standards for drinking water, monitors and enforces treatment techniques for surface water and groundwater, sets maximum limits for around 100 contaminants ensuring public disclosure of deviations and discrepancies.
WaterToday opens the record books of the federal drinking water regulator to bring awareness to the local raw water supply and the compliance record of licensed water treatment facilities. The Louisiana Dept of Health inspects 1,263 licensed and active public drinking water facilities, reporting the results to the EPA. Check back here for drinking water news and alerts as they arise in LA.
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