By SUZANNE DOWNING
April 5, 2026 – The US Environmental Protection Agency has taken an initial step toward potentially regulating microplastics and pharmaceuticals in drinking water, announcing a new draft list of contaminants that could eventually lead to federal limits for public water systems.
The agency on Thursday released its draft Sixth Contaminant Candidate List (CCL 6), a procedural step under the Safe Drinking Water Act that identifies substances that may require future regulation.
For the first time, the list includes microplastics and pharmaceuticals as priority contaminant groups, along with certain “forever chemicals,” disinfection byproducts, dozens of chemicals, and several microbes that may be found in drinking water.
The move does not impose immediate new rules on water utilities. Instead, the list is used to guide research, monitoring, and data collection before the EPA determines whether national drinking water standards are warranted.
EPA Administrator Lee Zeldin said the decision reflects growing public concern about emerging contaminants.
“By placing microplastics and pharmaceuticals on the Contaminant Candidate List for the first time ever, EPA is sending a clear message: we will follow the science, we will pursue answers, and we will hold ourselves to the highest standards to protect the health of every American family,” Zeldin said in a statement announcing the draft list.
The announcement came during an event with Health and Human Services Secretary Robert F. Kennedy Jr., where officials framed the effort as part of the administration’s “Make America Healthy Again” initiative focused on environmental exposures and public health.
Microplastics, tiny plastic particles that can result from the breakdown of larger plastics, have been detected in human blood, breast milk, and organs, according to some studies. Researchers are still working to determine what health risks, if any, those exposures may pose.
Pharmaceuticals in drinking water typically enter water systems through human waste or improper disposal of medications. The EPA said the category includes antidepressants, hormones, antibiotics, and other drugs. The agency is also releasing human health benchmarks for 374 pharmaceuticals, intended as guidance for states, tribes, and local water systems evaluating potential risks.
In Arizona, for example, Lake Mead and the ground water and wells in Gilbert, Glendale, and Goodyear have been found to contain pharmaceuticals such as acetaphinophen, hormones, and sunscreen ingredients such as oxybenzone.
The draft list also includes groups of per- and polyfluoroalkyl substances, commonly known as PFAS or “forever chemicals,” as well as byproducts created during drinking water disinfection processes such as chlorination.
Under federal law, the EPA must publish a contaminant candidate list every five years identifying substances that are not currently regulated but may warrant future standards. Inclusion on the list does not guarantee regulation.
The agency will use the information to conduct further research and determine whether the contaminants occur frequently enough, and pose sufficient health risks, to justify enforceable limits.
The draft CCL 6 will be published in the Federal Register, opening a 60-day public comment period. The EPA will also consult its Science Advisory Board before finalizing the list, which is expected later this year.
If the agency ultimately decides to regulate any of the listed contaminants, it would begin a separate rulemaking process that could take years before binding limits on drinking water systems are established.
