Revisions to the Unregulated Contaminant Monitoring Rule (UCMR)
Beginning in 2023, public water systems will be required to monitor for 29 per- and polyfluoroalkyl substances (PFAS) and lithium in drinking water. The requirement is part of the fifth Unregulated Contaminant Monitoring Rule (UCMR5), which was published by the United States Environmental Protection Agency (US EPA) on December 27, 2021. UCMR5 is just the latest revision to the UCMR, which allows the US EPA to gather data about emerging drinking water contaminants. As part of the Safe Drinking Water Act (SDWA), the US EPA proposes a new list of up to 30 contaminants for monitoring every 5 years. The 5-year span covered by UCMR5 allows for planning in 2022, sample collection and analysis from 2023-2025, and data reporting in 2026. The US EPA undergoes a multi-tiered process for selecting which contaminants will be monitored under each revision to UCMR. It starts by identifying contaminants expected to occur in drinking water systems nationally, which are not subject to regulation under the SDWA, and which have approved and validated drinking water methods. The US EPA also considers the degree of public concern, any critical health endpoints, and cost effectiveness of the applicable analytical methods, among other factors.
This is not the first time that PFAS compounds have been included as part of UCMR. Six PFAS compounds were part of UCMR3: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA), and perfluorononanoic acid (PFNA) were monitored from 2013-2015, though with higher minimum reporting limits (MRLs) than in UCMR5. Previous UCMR lists have also included known carcinogenic volatile organic compounds, viruses, cyanotoxins, pesticides, herbicides, insecticides, brominated haloacetic acid (HAA) disinfection byproducts, and various metals. The number of contaminants to be monitored in each revision of UCMR has been similar (25-30), but the previous revisions represented a broader range of contaminants. The overwhelming abundance of PFAS on the UCMR5 contaminant list clearly represents the national focus on PFAS and was a US EPA Priority Action identified in its PFAS Action Plan (February 2019). Additionally, the National Defense Authorization Act (NDAA) for Fiscal Year 2020 required that the US EPA include all PFAS within the scope of approved US EPA Methods 533 and 537.1 as part of the UCMR.
The US EPA estimates that approximately one-third of all public water systems will collect samples as part of UCMR5, with more than 4,000 large systems (those serving more than 10,000 customers) being required to participate. The US EPA will cover the costs associated with monitoring for small systems (all public water systems serving 3,300-10,000 customers and a representative sampling of systems serving fewer than 3,300 customers) pending the availability of appropriations and laboratory capacity. Samples are to be collected 2-4 times per year at all entry points to the distribution system for surface water (SW), groundwater under the direct influence of surface water (GWUDI), mixed sources (MX), and groundwater (GW) systems.
All laboratories performing analyses for UCMR5 were to have completed the necessary registration form and application for US EPA approval before August 1, 2022. All participating water systems (regardless of size) have until December 31, 2022, to register with the US EPA’s web-based reporting system, accept the provided notification letter, and update sampling location(s) and contact information.
The data collected from UCMR5 will provide much needed information about how prevalent these contaminants are in our water systems and at what levels. It will also allow scientifically sound decisions to be made about regulating these chemicals moving forward.