EPA Faces Backlash Over Drinking Water Monitoring Plan
The Environmental Protection Agency (EPA) has released a draft of a new drinking water monitoring plan that fails to include review of microplastics, despite calls from 176 organizations, seven governors and 14 attorneys general.
The proposal outlines the agency’s Sixth Unregulated Contaminant Monitoring Rule (UCMR 6), which identifies contaminants that public water systems will be required to monitor between 2028 and 2030.
Because the rule is updated only once every five years, the omission means microplastics are unlikely to be included in a nationwide federal monitoring program until at least the next UCMR cycle, unless the EPA changes course before the rule is finalized.
The Trump administration has emphasized its “Make America Healthy Again” (MAHA) agenda while also arguing that new environmental policies should be grounded in validated scientific methods.
EPA Administrator Lee Zeldin signed the proposed rule, and Assistant Administrator for Water Jessica Kramer said the agency’s approach reflects “gold standard science,” arguing that monitoring requirements should be based on validated analytical methods capable of producing reliable national data.
At the same time, the administration has also increased federal research into microplastics. Earlier this year, Health and Human Services Secretary Robert F. Kennedy Jr. announced a $144 million federal research initiative called STOMP (Systemic Targeting of MicroPlastics) under ARPA-H (Advanced Research Projects Agency for Health). This was to better understand human exposure to microplastics and their potential health effects, underscoring growing bipartisan interest in the issue even as regulators stop short of requiring nationwide drinking water monitoring.
Microplastics are plastic particles ranging in size from 5 millimeters (mm), which is about the size of a pencil eraser, to 1 nanometer (nm) and some research has suggested they can bioaccumulate in the human body and cause damage to certain cells among other health impacts.
The EPA updates the UCMR every five years to collect nationwide data on contaminants that are not yet subject to federal drinking water standards but could warrant future regulation.
While inclusion on the monitoring list does not automatically lead to new limits, the program provides the occurrence data the agency relies on when determining whether a contaminant poses a widespread enough concern to justify national drinking water standards.
For scientists and public health advocates, the decision over which contaminants are included can shape federal research and regulatory priorities for years.
States, Scientists and Advocacy Groups Push for Monitoring
The EPA’s decision follows a sustained campaign urging the agency to include microplastics in UCMR 6.
In November 2024, 176 organizations submitted a petition asking the EPA to add microplastics to the monitoring program. That effort was followed by a joint letter from the state governors of New Jersey, Delaware, Illinois, Maryland, Wisconsin, Michigan, and Connecticut in late 2025 making a similar request; New Jersey Attorney General Jennifer Davenport was the leader of the AG coalition. Under Section 1445 of the Safe Drinking Water Act, a petition signed by seven or more state governors triggers a specific legal mechanism that the EPA must address.
More recently, the attorneys general of 14 states and Washington, D.C. urged the agency to require monitoring for microplastics in comments submitted on the draft Sixth Contaminant Candidate List (CCL 6). Earlier this year, an additional 250 health professionals and organizations also called on the EPA to include microplastics in UCMR 6.
One of the organizations that submitted the November 2024 petition, Food and Water Watch, deemed the EPA’s proposal “disgraceful.”
“The current research on microplastics has repeatedly shown how disastrous this crisis is,” Food and Water Watch Water Policy Director Mary Grant said in a statement. “We need comprehensive monitoring data now to know how prevalent these contaminants are in our drinking water. EPA must reconsider its position and add microplastics to the final rule.”
Vinka Oyanedel-Craver, a professor of civil and environmental engineering at the University of Rhode Island, told Newsweek that this was “concerning.”
“The science is still developing, but I think we already know enough to justify national monitoring of microplastics in drinking water,” she said.
Nathaniel Warner, a professor of civil and environmental engineering at Penn State University, told Newsweek “there is increasing evidence that microplastics are linked with negative health outcomes,” and “without the inclusion of microplastics, we will not have a national data set to assess occurrence or ability to assess exposure.”
What Is Included in EPA’s UCMR 6 Proposal?
The EPA’s proposed UCMR 6 would require public water systems nationwide to test for a new set of unregulated contaminants in drinking water, continuing a program mandated under the Safe Drinking Water Act to collect occurrence data every five years.
Under the draft proposal, participating public water systems would monitor for 30 contaminant categories between 2028 and 2030.
The proposed list includes several groups of PFAS (“forever chemicals”), trifluoroacetic acid (TFA) and other ultrashort-chain organofluorine compounds, pesticide degradates, industrial chemicals and additional emerging contaminants selected because of their potential occurrence in drinking water and the availability of validated analytical methods.
Testing would generally apply to medium and large public water systems, along with a nationally representative sample of smaller systems, allowing the EPA to build occurrence data that could support future regulatory decisions.
Although microplastics are not included in UCMR 6, they do appear on the draft Contaminant Candidate List 6 (CCL 6). The CCL identifies contaminants that are known or anticipated to occur in public water systems and may require regulation in the future, but listing a contaminant does not itself require utilities to conduct monitoring.
The EPA has opened a 60-day public comment period on the draft UCMR 6 proposal before issuing a final rule. The agency also plans to hold two public informational webinars on August 11 and August 12, 2026, to explain the proposal and answer questions from stakeholders.
Why the EPA Says Microplastics Were Left Out
The EPA told Newsweek that it will “collaborate with other federal agencies to evaluate risks and exposures of microplastics to enable future monitoring for those microplastics that present potential health risks,” and that this approach will also enable the agency to “list microplastics on a future UCMR when national monitoring is scientifically feasible through the availability of a validated drinking water analytical method.”
The agency told Newsweek that if microplastics were included on UCMR 6, the public water systems subject to this rulemaking would be “unable to successfully monitor for microplastics.” There is no “validated EPA or consensus drinking water analytical method with the proper quality control data, accuracy, and precision that could be used for UCMR 6.”
It said that it “acknowledges the interest in and concern for microplastics in drinking water, and believes that including these contaminants on the draft CCL 6 as a first step in responding to the petition will prioritize the research that is needed to define and better understand the characteristics of microplastics that are associated with the public health risk.”
What Are Microplastics?
Microplastics generally fall into two categories: primary microplastics, which are intentionally manufactured for use in products like cosmetics or medical applications, and secondary microplastics, which form when larger plastic items-such as bottles, packaging, or synthetic clothing-break down over time.
Scientists say these particles are now widespread in the environment, detected across ecosystems from oceans and rivers to air, food, and even human tissue.
Microplastics can also degrade into smaller nanoplastics through chemical weathering processes, mechanical breakdown, and even through the digestive processes of animals. Nanoplastics are a subset of microplastics and they are smaller than 1 micrometer or 1000 nanometer-they cannot be seen by the human eye.
Oyanedel-Craver told Newsweek microplastics enter drinking water systems “through the water cycle.” This means that airborne particles can “deposit into reservoirs and surface waters, while polluted stormwater runoff can carry plastic fragments into rivers, lakes, and groundwater.”
Warner said that clothing is also a source of microplastics, as the washing and drying of clothes “releases microplastic fibers from our clothes,” and that mismanagement or litter of single-use plastics like straws and plastic bags is another key contributor.
Oyanedel-Craver added that while conventional drinking water treatment can remove many particles, the “smallest fraction is harder to detect and remove, and it may be the most relevant for human exposure.”
What Do Scientists Know About the Health Risks?
The health effects of microplastics remain an area of rapidly evolving research, with scientists cautioning that many important questions have yet to be answered.
People may be exposed through drinking water, food, inhalation of airborne particles and, in some cases, skin contact. Researchers have detected microplastics in multiple human tissues, but scientists are still investigating how different particle sizes, concentrations and chemical compositions influence health.
Laboratory studies and animal research suggest that some microplastics can trigger inflammatory responses, oxidative stress, immune system changes and disruptions to the gut microbiome. However, translating those findings into direct human health outcomes remains an active area of investigation.
Clinical and epidemiological evidence has also expanded. A December 2025 review published in The Lancet Planetary Health concluded that exposure to microplastics and nanoplastics is associated with a range of adverse health outcomes-including cardiovascular, respiratory, metabolic and neurological conditions-but the authors emphasized that the evidence does not yet establish direct causation in humans and that higher-quality long-term studies are still needed.
Scientists say one reason the research remains challenging is that people are exposed to countless types of plastic particles throughout their lives, making it difficult to isolate the health effects of any single source or level of exposure.
Researchers are also concerned about more than the plastic particles themselves.
“Microplastics are not only small pieces of polymer, such as PET, PVC or PS,” Oyanedel-Craver said. “They can also contain hundreds of chemical additives, some of which are known to be toxic or carcinogenic.”
Those additives-as well as pollutants and microorganisms that can adhere to plastic particles in the environment-may influence how microplastics interact with the body, though researchers are still studying the extent of those risks.
Oyanedel-Craver said important scientific uncertainties should not be mistaken for evidence that the contaminants are harmless.
“It is true that we do not fully understand their behavior inside the body,” she added. “That does not mean there is no risk.”
She said nationwide monitoring could help answer many of the remaining questions by establishing where microplastics occur, how concentrations vary across drinking water systems and how potential exposure changes over time.
Without consistent national monitoring data, researchers say it will remain more difficult to understand population-level exposure, evaluate treatment technologies and determine whether future federal drinking water standards are warranted.
Contact Newsweek editors on this story: Daniel Orton and James Debens.
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This story was originally published June 30, 2026 at 9:08 AM.