UCMR 5: Its Role in Detecting Emerging Contaminants in Drinking Water


Over the last few decades, EPA and other regulatory agencies have set strict guidelines and standards to ensure that public water systems are providing clean and safe drinking water to their customers. In addition to the contaminants that all systems have to test for—such as those found in disinfectants, disinfection byproducts, and other various organic and inorganic chemical contaminants—the 1996 amendments to the Safe Drinking Water Act (SDWA) require that EPA must issue a list of no more than 30 unregulated contaminants to be monitored by water systems every five years. As a result, EPA established the UCMR program to gather nationally representative data for unregulated contaminants and improve their understanding of their occurrence. Similar to how EPA handled PFAS contamination by implementing the PFAS Strategic Roadmap, this data will help inform future regulatory decisions to protect public health.

The latest iteration on EPA's list of unregulated contaminants in public water systems is the fifth Unregulated Contaminant Monitoring Rule (UCMR 5), published in December 2021. Emerging contaminants, which are currently unregulated but potentially harmful chemicals, are a growing concern. In this article, we will discuss the UCMR program and the emerging contaminants to be aware of, providing a comprehensive update on the latest developments and how to ensure that your system is compliant in the event of future regulation.

UCMR 5 and Monitoring for Emerging Contaminants in Drinking Water  

UCMR 5 mandates sample collection for 30 contaminants between 2023 and 2025, with the aim of understanding their frequency and levels in drinking water systems across the country. UCMR 5 expands the list of contaminants already regulated by EPA by requiring testing for unregulated contaminants—particularly those deemed "emerging contaminants"—including 29 PFAS and lithium.  

UCMR 5 also significantly expands the number of water systems participating in the program. Previous UCMR programs required that all public water systems serving more than 10,000 people monitor for contaminants. UCMR 5 also requires all large water systems to participate, but extends monitoring requirements to 800 randomly selected representative systems serving fewer than 3,300 people, and most systems serving 3,300 people or more.

Systems required to participate have already been notified by the agency. EPA has also promised to give six-month notice to any additional small systems that will be required to participate in the program.

What are Emerging Contaminants?

As part of the UCMR 5 program, samples will be collected and analyzed for 30 emerging contaminants. Emerging contaminants are chemicals characterized by a perceived, potential, or real threat to human health or the environment, and therefore have been identified as 'contaminants of emerging concern'. Anything that isn't regulated by the EPA is considered 'emerging'. Frequently, the driving force behind the identification of these emerging contaminants is the development of new testing methods, which allows for detection of previously unknown substances in drinking water and other sources. These chemicals can originate from various sources, including pharmaceuticals, personal care products, pesticides, herbicides, and industrial chemicals. Due to their only recent recognition as potential risks to public health, these contaminants are not yet subject to EPA regulations.

Emerging contaminants enter the environment every day through use of chemical-based products. Once these chemicals enter rivers, lakes, and streams, they can persist within the ecosystems for long periods of time. Measurable quantities of these contaminants are passed through the environment and food chain through fish, predatory wildlife, and eventually to humans. Even at low levels, studies have shown that PFAS can be harmful to human and animal health, including hormone disruption, developmental problems, and cancer. Due to the potential risks associated with PFAS and the emerging contaminants, it is important to monitor for their presence in drinking water.

Emerging Contaminants that Water Systems Should Know

There are several emerging contaminants of which water systems should be aware. UCMR 5 includes 30 emerging contaminants: 29 PFAS chemicals and lithium. A full list of the contaminants included in UCMR 5—along with their minimum reporting levels, sampling locations, and analytical methods—can be found on the EPA website.

How to Ensure Compliance with UCMR 5 Monitoring Requirements

To prepare for UCMR 5 sampling, it is important to follow the required sampling protocols and submit the necessary information through EPA’s web-based reporting system, Safe Drinking Water Accession and Review System (SDWARS), accessed through EPA’s Central Data Exchange.  

As with previous UCMR programs, representative sampling for multiple groundwater wells can be conducted if several qualifications are met, including that the wells are in close proximity to each other and draw from the same source as the representative sample, and the sample represents wells with the highest volume and most activity. It is also important that the source is in use at the time of sampling.

Groundwater sources must submit 2 samples collected 5-7 months apart, while surface water or other mixed sources must collect 4 quarterly samples. In addition to water quality monitoring, water systems will be asked to submit other information like service area zip codes, disinfectant types, and treatment processes. UCMR 5 will also require data on previous PFAS and lithium testing, along with any prior awareness of potential PFAS contamination.

Aside from staying informed about the sampling and data submission requirements, there are several other ways for water systems to ensure compliance with UCMR 5 monitoring requirements:

  1. Develop a sampling plan that outlines the locations, timing, and frequency of sample collection. This plan should be based on the system's source, size, and treatment processes.
  1. Ensure that samples are collected and analyzed according to EPA guidelines and using approved analytical methods. This includes shipping samples to the laboratory in a timely manner.
  1. Maintain accurate records of all monitoring activities and report monitoring results to the EPA through the SDWARS.

While adhering to the sampling and data submission requirements is crucial for UCMR 5 compliance, there are other challenges that water systems may face when implementing the program.

UCMR 5 and the Challenges of Compliance

There are several common issues water systems may face in complying with UCMR 5 monitoring requirements.  

  1. UCMR requires frequent sampling and a large number of contaminants to account for. While EPA is responsible for the analytical costs associated with monitoring for systems serving 10,000 or fewer, EPA does not cover all other associated costs. This means costs associated with sampling are incurred by small water systems while both sampling and analysis costs are incurred by large water systems. EPA estimates the total average national cost of UCMR 5 will be $21 million per year over five years, leaving water sources to carry a massive financial burden.  
  1. The analytical methods used to detect UCMR 5 contaminants can be complex and depend on the specific contaminant being tested. The specialized equipment and expertise required for such methods can be costly and difficult to obtain, particularly for small water systems with limited resources.  
  1. If emerging contaminants are detected above the UCMR reporting levels, systems will have to set up a comprehensive action plan for cleanup. PFAS cleanup itself can cost millions of dollars and require years or even decades of ongoing operations and maintenance, making it important to have a cost recovery strategy in place. Therefore, systems that detect PFAS in their water supply will likely want to establish effective communication strategies, treatment options for PFAS contamination, and a plan for cost recovery.  

To offset the costs involved with testing and treatment, one prominent option is to use the legal process to hold the manufacturers of the products containing PFAS accountable. Law firms with extensive water contamination litigation experience can help water systems by providing regulatory updates, litigation advice, and handling time-consuming work required to prepare to file a lawsuit. Plus, many law firms work on a contingency fee basis, meaning that water systems will not incur any fees unless the case is successfully resolved. This means there are often zero drawbacks to seeking legal counsel, as they will provide the necessary information and support to maintain momentum towards an effective cost recovery solution—with no financial risk.


Water systems that fall within the mandated group or have received a notification should begin monitoring and reporting emerging contaminant levels for UCMR 5. It is also important for systems to take proactive steps to prepare for public communication, treatment options, and cost recovery.  

At SL Environmental Law Group, we have over 20 years of water contamination litigation experience against large chemical manufacturers. Thanks to our decades of experience, we can help you comply with UCMR 5, stay knowledgeable about emerging contaminants, and provide legal guidance for cost recovery solutions.

For more information on navigating UCMR 5 and beyond, set up your confidential and complimentary consultation.