EPA PFAS Monitoring Excludes Microplastics

CLIFF NOTES

• EPA proposed UCMR 6 on July 1, 2026.
• Water systems would monitor 30 unregulated contaminants from 2028 through 2030.
• The list includes certain PFAS and other organic compounds.
• EPA excluded microplastics because no validated national drinking water test method is ready.
• Microplastics remain on draft CCL 6 and are the subject of continued federal research.

The U.S. Environmental Protection Agency proposed the Sixth Unregulated Contaminant Monitoring Rule, known as UCMR 6, on July 1, 2026. The proposal would require thousands of public water systems to test for 30 unregulated contaminants from 2028 through 2030. Certain PFAS are included, but microplastics are not.

The central point: EPA is expanding national drinking water monitoring for certain PFAS and other emerging contaminants, while delaying microplastics monitoring because no validated federal test method is ready. Microplastics remain under federal review through a separate candidate-list process and a new national research program.

What Does the UCMR 6 Proposal Require?

UCMR 6 is part of the federal process for identifying contaminants that may be present in drinking water but are not yet regulated under the Safe Drinking Water Act.

The program does not automatically establish a drinking water limit. It gathers national occurrence data. That data can show where contaminants are found, how often they appear and how many people may be exposed. EPA may later use those findings when deciding whether a national drinking water standard is needed.

EPA’s proposal covers 30 chemical contaminants divided among four analytical methods:

• Seven ultrashort organofluorine compounds, including certain PFAS, tested through EPA Method 563
• Three pesticide metabolites tested through EPA Method 540
• Thirteen semi-volatile organic compounds tested through EPA Method 525.3
• Seven purgeable organic compounds tested through an enhanced-sensitivity version of EPA Method 524.3

Sampling would begin in January 2028 and continue through December 2030. EPA describes the monitoring as a foundation for future public-health decisions.

Which Water Systems Would Have to Monitor?

The proposal would require monitoring by:

• Large community water systems serving more than 10,000 people
• Non-transient, non-community systems serving more than 10,000 people
• Systems serving between 3,300 and 10,000 people
• A nationally representative group of systems serving fewer than 3,300 people

Participation by the smallest systems would depend on federal funding and available laboratory capacity.

EPA estimates a total national cost of approximately $33.7 million per year in 2025 dollars. Under the proposal, the agency would cover analytical testing costs for water systems serving 10,000 or fewer people.

The structure reflects a simple reality: national drinking water decisions require national data. UCMR 6 is designed to create that record before future standards are considered.

Why Are PFAS a Major Part of UCMR 6?

PFAS are synthetic chemicals used because they resist water, heat, oil and stains. They have appeared in products such as firefighting foam, food packaging, cookware, carpeting, cosmetics, clothing and industrial coatings.

The Holland & Knight alert by Matthew Z. Leopold, Clarissa Howley Mills, Dianne R. Phillips and Maggie P. Pahl describes PFAS as synthetic “forever chemicals.” The phrase reflects the resistance of many PFAS compounds to natural breakdown.

Several of the seven ultrashort organofluorine compounds proposed for monitoring are considered PFAS. Their inclusion continues EPA’s broader effort to identify and address PFAS contamination in drinking water.

EPA has used earlier UCMR cycles for the same purpose. UCMR 5 required systems to monitor for 29 PFAS compounds and lithium between 2023 and 2025.

EPA also established the first national drinking water limits for certain PFAS in 2024. Those standards later faced industry litigation, including arguments that EPA lacked sufficient occurrence data before setting the limits.

UCMR 6 could therefore influence more than future regulation. The monitoring results may also shape legal arguments about the quality and amount of evidence available to EPA.

Why Did EPA Exclude Microplastics?

EPA declined to place microplastics on the UCMR 6 monitoring list because the agency does not yet have a validated drinking water test method that meets the program’s requirements for accuracy, precision and quality control.

The decision followed petitions submitted on November 26, 2025, by the governors of Connecticut, Delaware, Illinois, Maryland, Michigan, New Jersey and Wisconsin. Supporting environmental organizations submitted a related petition.

The Safe Drinking Water Act allows seven or more governors to petition EPA to add a contaminant to an unregulated monitoring rule. EPA may decline when adding that contaminant would interfere with monitoring substances considered a higher public-health priority.

In this case, EPA’s stated obstacle was analytical readiness. A national monitoring program depends on laboratories producing comparable results. Without a validated method, different laboratories could count, classify or measure plastic particles in different ways.

That would weaken the national dataset UCMR is intended to produce.

EPA plans to continue evaluating existing technical approaches, including ASTM D8332-20 and ASTM D8333-20. The agency also intends to work with other federal departments on research into exposure and health risks.

California has already moved further at the state level. In September 2022, the California State Water Resources Control Board adopted a policy handbook for testing and reporting microplastics in drinking water.

Are Microplastics Still an EPA Priority?

Microplastics remain a federal priority even though they were left out of UCMR 6.

EPA placed microplastics on its draft Sixth Contaminant Candidate List, or CCL 6, in April 2026. The draft contains:

• 75 individual chemicals
• Four chemical groups
• Nine microbial contaminants

The four groups are microplastics, PFAS, pharmaceuticals and disinfection byproducts. EPA has described microplastics as a priority contaminant group within the draft list.

The distinction between UCMR 6 and CCL 6 matters.

UCMR 6 creates occurrence data through required monitoring. CCL 6 identifies contaminants that are known or expected to occur in public water systems and may require future regulation.

The programs operate on separate five-year cycles, but they support the same regulatory process. Monitoring data can help build future candidate lists. Candidate-list research can eventually support monitoring, regulatory determinations or national maximum contaminant levels.

EPA expects to finalize CCL 6 after reviewing public comments and the available scientific record.

What Are Microplastics?

Microplastics are small plastic particles generally ranging from about one nanometer to five millimeters.

Their size, shape and chemical composition can vary widely. Some are manufactured at a small size. Others form when larger plastic products break down.

The scientific challenge lies in that variety. Researchers must determine how to identify different particles, measure exposure and distinguish microplastics from other material in water, tissue and environmental samples.

The source alert states that current evidence has not established clear exposure levels or dose-response relationships linking microplastics to specific harmful effects in humans, animals or the environment. That uncertainty is one reason federal research remains focused on measurement and biological effects rather than enforceable drinking water limits.

How Is the Federal Government Studying Microplastics?

In April 2026, the Advanced Research Projects Agency for Health announced the Systematic Targeting of MicroPlastics program, known as STOMP.

The $144 million program is intended to create tools for measuring, studying and potentially removing microplastics and nanoplastics from the human body. ARPA-H says the work will include improved laboratory measurements and research into how particles move through organs and cells.

STOMP illustrates the stage at which federal microplastics policy currently stands. The first task is measurement. The second is understanding exposure and biological effects. Regulatory limits can follow only when those earlier steps produce reliable evidence.

Federal microplastics law remains limited. Existing measures include the Microbead-Free Waters Act of 2015 and the Save Our Seas 2.0 Act of 2020. Several states also regulate microbeads or other forms of plastic pollution.

Why Does UCMR 6 Matter to Water Systems and Communities?

For public water systems, UCMR 6 could create new sampling, reporting, laboratory and administrative duties.

For regulators, the data could reveal where the listed contaminants occur and whether certain system sizes, water sources or regions face greater exposure.

For researchers, the results could identify knowledge gaps and guide future toxicology or treatment studies.

For communities, the monitoring could make previously invisible contamination patterns easier to identify. A contaminant’s presence does not automatically establish a health violation, especially when no national standard exists. It does, however, create evidence that can influence treatment decisions, public communication and future regulation.

The proposal also shows why testing methods matter. A contaminant can remain outside a national monitoring rule even when policymakers consider it important. Without a consistent way to measure it, the evidence remains fragmented.

What Happens Next?

EPA must review comments on the UCMR 6 proposal before issuing a final rule. Water systems, laboratories, industry groups, environmental organizations and state agencies may submit information about testing methods, costs, system capacity and contaminant selection.

If finalized substantially as proposed, monitoring would take place from 2028 through 2030.

Microplastics could appear in a later UCMR cycle once EPA validates a suitable analytical method and enough laboratories can perform the work consistently.

The exclusion should therefore be understood as a delay in national monitoring rather than removal from federal policy. Microplastics remain on the draft CCL 6, and federal agencies continue to fund research into measurement, exposure and health effects.

How Do Home Water Treatment Systems Relate to PFAS and Emerging Contaminants?

UCMR 6 applies to public water systems. It does not require individual households to install filtration equipment.

Still, national monitoring may lead residents to examine the quality of water entering their homes. A home water test can help identify measurable water-quality conditions and determine whether further laboratory analysis is appropriate. East Coast Water Quality offers this service for free for Virginia and North Carolina customers, however we do not test for PFAS, but we do offer solutions for them. To see what PFAS are in your water enter your zip code at the EWG Tap Water Database.

A reverse osmosis drinking water system treats water at the point where it is used for drinking and cooking. Properly designed reverse osmosis systems can reduce many dissolved contaminants, including certain PFAS, lead, nitrates, arsenic and excess dissolved solids. Actual reduction depends on the system, water chemistry, maintenance and contaminant involved.

A whole-home water conditioner serves a different purpose. It can address hardness minerals, chlorine, sediment and scale-related problems throughout a house. It should not be treated as a substitute for contaminant-specific drinking water filtration unless the system is designed and verified for that contaminant.

East Coast Water Quality has served Virginia and North Carolina for more than 12 years. Its available systems include reverse osmosis drinking water filtration and whole-home treatment equipment backed by lifetime warranties.

In Short

The proposed UCMR 6 PFAS monitoring rule would create a new national record for 30 unregulated drinking water contaminants between 2028 and 2030.

PFAS remain at the center of EPA’s monitoring and regulatory agenda. Microplastics remain outside UCMR 6 because a validated national test method is not ready, but they remain on the draft CCL 6 and within major federal research programs.

The sequence is deliberate. Reliable measurement creates dependable data. Dependable data supports defensible decisions. UCMR 6 represents the next stage of that process.

Source: Holland & Knight