Overview of Additions to CCL 6
On April 2, 2026, the United States Environmental Protection Agency (EPA) announced that per- and polyfluoroalkyl substances (PFAS), microplastics, pharmaceuticals, and disinfection byproducts, along with dozens of other chemicals and microbes, will be added to the draft of its Sixth Contaminant Candidate List (CCL 6). Updated every five years, the CCL identifies contaminants known or anticipated to be present in public water systems.
Regulation of PFAS, microplastics, pharmaceuticals, and disinfection byproducts has been an ongoing discussion among federal, state and local agencies. The Biden Administration previously issued maximum contaminant levels (MCLs) in drinking water for select PFAS, including PFOA, PFOS, GenX chemicals, and mixtures of certain variants. Initially, the Trump Administration rolled back Biden-era PFAS drinking water MCLs and extended the deadline to comply with remaining regulations, softening regulatory and enforcement structures. However, the addition of PFAS on the draft CCL 6 signifies a reversal in the Trump Administration’s policy and suggests a trend towards increased regulation. States have also pushed for similar regulations. In June 2025, California’s Department of Toxic Substances Control added microplastics to the state’s CCL for potential regulation. Likewise, Illinois, Hawaii, Vermont, Colorado, and New Jersey introduced legislation in early 2026 that targets microplastics in drinking water, state waters, wastewater, personal care products, cleaning products, and washing machines.
The identification of PFAS, microplastics, pharmaceuticals, and disinfection byproducts on the EPA’s draft CCL 6 came amid the US Department of Health and Human Services’ (HHS) announcement that outlines a set of actions to safeguard the nation’s drinking water, identified as a central component of the “Make American Healthy Again (MAHA)” movement. HHS announced a Systematic Targeting of MicroPlastics (STOMP) initiative and pledged $144M towards research that measures microplastics in human tissue and studies its biological effects. The inclusion of these potential contaminants in the CCL 6 draft reflects an effort to respond to public requests for improved drinking water quality and analysis of potential impacts these substances could have on human health and the environment. Research generated from the STOMP initiative could be used to advise future regulation and enforcement of these chemicals.
Reaction and Impact
While environmental and clean drinking water activists express that addition of PFAS, microplastics, pharmaceuticals, and disinfection byproducts to the CCL is a good first step, they claim it merely formalizes the identification of contaminants the public is already aware of and does little to address potential health and safety risks. Activists also argue there is a significant amount of data and research readily available for EPA to regulate, rather than monitor, these substances.
Although the draft CCL 6 identifies PFAS, microplastics, pharmaceuticals, and disinfection byproducts as potential contaminants, the CCL’s scope is limited to public water systems and does not expand to other environmental media. In fact, EPA has since declined to adopt several states’ requests to identify PFAS as air pollutants. Specifically, in August 2024, North Carolina, New Jersey and New Mexico petitioned the EPA to deem certain PFAS as hazardous air pollutants under the Clean Air Act (CCA). Generally, the EPA must reply to such a petition within 18 months of receipt, but to date, it has not yet done so. Because the EPA’s deadline to respond was March 2026, Petitioner States are currently evaluating next steps. However, inclusion of similar PFAS variants in the draft CCL 6 may suggest an increased willingness by EPA to monitor and manage these substances under other regulatory schemes, such as the CCA.
Looking Forward
Upon publication of the draft CCL 6, the public is afforded a 60-day period that ends June 5, 2026, to provide comments on the proposed list before it is finalized on November 17, 2026. Even when finalized, no regulations are immediately or automatically impacted by updates to the CCL. Rather, the CCL serves as an overall guide for the EPA to identify new contaminants for future regulation; thus, the addition of new contaminants simply suggests efforts to prioritize research, data collection, and monitoring of substances identified therein.
Although the inclusion of PFAS, microplastics, pharmaceuticals, and disinfection byproducts on the draft CCL 6 does not immediately signify new regulations, affected stakeholders and industries should monitor the regulatory landscape for future regulations, litigation risks, disclosure considerations, reporting requirements, supply assessment, and opportunities for proactive engagement. The Trump Administration’s policy reversal also suggests that regardless of the party in power, steps taken to negate or minimize potential adverse human health and environmental risks associated with chemicals, synthetic or natural, will be prioritized going forward.
What to Watch and How to Engage
Affected stakeholders, including manufacturers, sellers, suppliers, distributors, and other related businesses and entities, should submit their positions and concerns regarding the EPA’s draft CCL 6 before the June 5 public comment deadline, especially since the final CCL, set to be published on November 17, 2026, could initiate subsequent monitoring and research of PFAS, microplastics, pharmaceuticals, and disinfection byproducts in drinking water and other environmental media. While it seems unlikely that new regulations related to these potential contaminants will be introduced in the coming months, investigative and regulatory actions could significantly impact manufacturers and other industry participants following the November finalization.
Similarly, even without formal regulations, litigation pertaining to PFAS, microplastics, pharmaceuticals, and disinfection byproducts will ensue before finalization of the CCL. Hence, companies and supply chain partners should proactively review internal records, conduct assessments, coordinate oversight strategies among communication, legal, and other departments, and take additional actions to plan and prepare for future regulatory and litigation challenges.
MG+M Law Clerk Tess Bedingfield is a contributing author of this article.
