EPA Proposes UCMR 6 for PFAS and Other Contaminants, Declines Adding Microplastics

The U.S. Environmental Protection Agency (EPA) proposed the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) on July 1, 2026. The proposed rule would require public water systems to collect national data on 30 unregulated contaminants that are not currently subject to national primary drinking water regulations under the Safe Drinking Water Act (SDWA). The 30 contaminants fall into four groups, each tied to an EPA drinking water test method: seven ultrashort organofluorine compounds – including certain per- and polyfluoroalkyl substances (PFAS) (EPA Method 563), three pesticide metabolites (EPA Method 540), 13 semi-volatile organic compounds (EPA Method 525.3) and seven purgeable organic compounds (EPA Method 524.3 Enhanced Sensitivity). Sample collection would run from January 2028 through December 2030.

The proposal requires monitoring by all large community water systems and non-transient, non-community water systems serving more than 10,000 people, as well as all systems serving 3,300 to 10,000 people and a nationally representative sample of systems serving fewer than 3,300 people, subject to available funding and laboratory capacity. EPA estimates the total annual national cost at $33.7 million (2025 dollars) and will pay the test costs for systems serving 10,000 or fewer people.

Notably, microplastics are not on the UCMR 6 list. On November 26, 2025, EPA received a petition from the governors of seven states – Connecticut, Delaware, Illinois, Maryland, Michigan, New Jersey and Wisconsin – requesting that the agency include microplastics under SDWA Section 1445(a)(2)(B)(ii). This provision directs EPA to include a contaminant recommended by a petition signed by the governors of seven or more states, unless doing so would prevent listing other contaminants of higher public health concern. EPA also received a related petition from supporting environmental organizations. Despite prior indications that microplastics were a federal priority, including its listing on the Sixth Contaminant Candidate List (CCL 6), EPA declined to add microplastics to the UCMR 6 list.

EPA's Draft CCL 6

CCL 6 is a list of unregulated contaminants that may require regulation, which EPA publishes every five years. EPA added microplastics to the draft CCL 6 in April 2026. The draft list includes 88 unregulated contaminants in total: 75 individual chemicals, four chemical groups (microplastics, PFAS, disinfection byproducts and pharmaceuticals) and nine microbial contaminants. EPA expects to finalize and sign the list by November 17, 2026.

CCL 6 and UCMR 6 are two connected steps in EPA's drinking water process under SDWA. The two programs run on separate, staggered five-year cycles. SDWA requires EPA to use UCMR 6 data to build future CCLs and decide whether to set a national standard such as a maximum contaminant level (MCL).

PFAS: A Central Focus of UCMR 6 and CCL 6

PFAS are synthetic "forever chemicals" valued for resisting heat, water and stains. They are widely used in food packaging, cookware, cosmetics, clothing, carpeting, coatings and firefighting foam, and they are a main focus of UCMR 6 and CCL 6. Of the seven ultrashort organofluorine compounds EPA proposes to monitor (all using EPA Method 563) under UCMR 6, several are considered PFAS. EPA frames this monitoring as consistent with its long-standing priority to address PFAS in drinking water under the 2019 PFAS Action Plan. (See Holland & Knight's previous alert, "EPA Releases Anticipated PFAS Action Plan," February 15, 2019.)

In 2024, EPA set the first national MCLs for certain PFAS. Industry members subsequently challenged the drinking water rule on the basis that EPA had not collected enough occurrence data before setting MCLs. Oral argument has been set in the pending litigation for September 18, 2026. UCMR 6 is the tool that generates this kind of occurrence data, so the PFAS data collected from 2028 to 2030 could shape both future regulation and litigation.

Why Microplastics Were Left Out of UCMR 6

EPA's stated reason for declining to list microplastics on UCMR 6 relates to the unavailability of accepted test methods. There is currently no validated EPA or consensus drinking water test method with the needed quality control, accuracy and precision that could be used for microplastics in UCMR 6. It is worth noting that California has adopted a standardized state methodology for microplastics in drinking water.

EPA said it will continue to evaluate existing techniques (ASTM D8332-20 and D8333-20) to develop validated methods and adequate laboratory capacity for a future UCMR and work with other federal agencies to assess risks and exposures. Listing microplastics on the draft CCL 6 may promote the type of research needed to establish a validated EPA test method.

Microplastics Regulation and Research: State and Federal Developments

Microplastics are plastic fragments generally between one nanometer and five millimeters, and the science is in preliminary stages. Current evidence does not establish exposure levels or dose-response relationships linking microplastic exposure to clear harmful effects in humans, animals or the environment.

Federal microplastics law is limited, consisting mainly of the Save Our Seas 2.0 Act (2020) and the Microbead-Free Waters Act (2015). Ten states regulate microplastics in some way – California, Colorado, Connecticut, Hawaii, Illinois, Indiana, Maine, Maryland, New Jersey and Wisconsin – most by banning microbeads. However, California has gone the farthest. Under Senate Bill 1422 (Health and Safety Code Section 116376), the California State Water Resources Control Board adopted a policy handbook in September 2022 establishing a standardized method for testing and reporting microplastics in drinking water.

On the research side, the Advanced Research Projects Agency for Health in April 2026 announced Systematic Targeting of MicroPlastics (STOMP), a $144 million national program to develop tools to measure, study and remove microplastics and nanoplastics in the human body.

What This Means

The microplastics decision is best read as a matter of timing, not retreat. By listing microplastics on CCL 6 and continuing to develop test methods, EPA keeps them on a path toward possible future UCMR monitoring and, eventually, possible regulation.

Microplastics also remain a stated federal health priority. The May 2025 Make America Healthy Again Commission report identified microplastics as a potential factor in chronic health problems in children and called for more research. Together, the CCL 6 listing and STOMP underscore continued federal momentum on microplastics. More research may generate data that influences litigation and could eventually support an MCL.

Next Steps

Holland & Knight's Environmental Team and Emerging Contaminants and PFAS Team are monitoring UCMR 6, the draft CCL 6 and related microplastics and PFAS developments. We can help clients assess exposure, evaluate compliance obligations, prepare public comments, and develop regulatory and litigation strategy.

For more information or questions on this matter, contact the authors or reach out to your Holland & Knight representative.

Information contained in this alert is for the general education and knowledge of our readers. It is not designed to be, and should not be used as, the sole source of information when analyzing and resolving a legal problem, and it should not be substituted for legal advice, which relies on a specific factual analysis. Moreover, the laws of each jurisdiction are different and are constantly changing. This information is not intended to create, and receipt of it does not constitute, an attorney-client relationship. If you have specific questions regarding a particular fact situation, we urge you to consult the authors of this publication, your Holland & Knight representative or other competent legal counsel.