The federal Safe Drinking Water Act (SDWA) requires that once every five years, the United States Environmental Protection Agency (EPA) publish a list of unregulated contaminants to be monitored by public water systems (PWS) for a period of time.  On December 27, 2021, EPA published its most recent list – the fifth Unregulated Contaminant Monitoring Rule (UCMR 5) – which will require sample collection for 30 chemical contaminants between 2023 and 2025.

In particular, UCMR 5 will include 29 per- and polyfluoroalkyl substances (PFAS) capable of being analyzed within the scope of EPA analytical methods 533 and 537.1, including HFPO DA (a component of GenX), PFNA, PFOS, and PFOA.  EPA provides the full list PFAS to be monitored on its UCMR 5 webpage, the associated minimum reporting level for each compound, the sample point location, and the analytical method to be used.  EPA states that it will use data collected through UCMR 5 to better understand the potential presence of PFAS in drinking water systems across the country and to inform future decisions under EPA’s PFAS Strategic Roadmap.

In UCMR 5, EPA identifies the following categories of PWS that will be required to monitor:

  1. All PWS that serve more than 10,000 people (Large Systems).
  2. PWS that serve between 3,330 and 10,000 people (Small Systems), subject to available EPA appropriations and EPA notification.
  3. 800 randomly selected systems that serve fewer than 3,000 people, subject to available EPA appropriations and EPA notification.

EPA is required under the SDWA to pay the “reasonable costs of such testing and laboratory analysis” for applicable PWS that serve 25 to 10,000 people.  Given this, EPA states that it will require monitoring at as many systems serving 25 to 10,000 people as appropriations support.  EPA states that by July 1 of each sampling year, it anticipates clarifying the monitoring obligations of affected systems based on the availability of appropriations each year.

EPA has published a list of laboratories that it has approved to analyze UCMR 5 samples:

EPA will hold two virtual public webinars regarding the implementation of UCMR 5 on March 16 and 17, 2022.  For more information on attending EPA’s public webinar, visit EPA’s webpage at