Posted

EPA Takes Steps to Regulate Microplastics, PFAS and Pharmaceuticals under the Safe Drinking Water Act

by and

The Safe Drinking Water Act (SDWA) is the primary federal law that protects drinking water quality and authorizes the EPA to promulgate regulations to limit harmful contaminants in public water systems. Under § 1412(b)(1)(B)(i) of the SDWA, the U.S. Environmental Protection Agency (EPA) must publish a Contaminant Candidate List (CCL) every five years identifying emerging contaminants that are not yet subject to a Maximum Contaminant Level (MCL) but that may pose a public health risk. CCLs are the first step in the SDWA regulatory process and are used to drive research into the listed contaminants to better understand health impacts, occurrence data, and risk levels. The CCL process is used to inform future regulatory action but does not impose any regulatory requirements in itself.

On April 2, EPA announced the release of the draft Sixth CCL (CCL 6) marking the first time that microplastics and pharmaceuticals have been designated as potential contaminants for regulation under the SDWA. The CCL 6 also lists, as a class, per- and polyfluoroalkyl substances (PFAS) and disinfection byproducts, as well as 75 chemicals and nine microbes.

  • Microplastics are tiny plastic particles measuring less than five millimeters in size that are ubiquitous in the environment and easily ingested by humans. Because this is the first time that microplastics have been included on the CCL, there are still significant data gaps and more investigation is necessary to determine detection methods, potential sources, and impacts on human health.
  • PFAS have been included on CCL lists as far back as 2009. The latest SDWA Unregulated Contaminant Monitoring Rule (UCMR 5) required regulated public water systems to sample for 29 PFAS chemicals. Notably, CCL 6 defines PFAS broadly, using the definition that EPA has developed for, among other things, the one-time PFAS Reporting Rule under Section 8(a)(7) of the Toxic Substances Control Act, 15 U.S.C. § 2601, et seq. This definition is notably controversial, as it includes fluoropolymers, which are widely used in commercial and industrial applications and do not present the same concerns of persistence, bioaccumulation, and toxicity as certain other types of PFAS (for example, long-chain alkyl acid PFAS). It remains to be seen which specific PFAS are selected for inclusion on the next UCMR list or for MCLs (similar to those finalized in 2024 for PFOA and PFOS).
  • The CCL employs a broad definition of pharmaceuticals, which covers any substance that meets the definition of a “drug” under the Federal Food, Drug, and Cosmetic Act (21 U.S.C. § 321).
  • Disinfection byproducts (DBP) are formed when disinfectants used for antimicrobial treatment in drinking water react with organic or inorganic materials. The EPA has listed 27 unregulated DBPs, 23 of which were previously listed on CCL 5.

EPA is seeking comments on the draft CCL 6 as well as on the process used to select the contaminants. Comments must be received on or before June 01, 2026.