EPA Unveils Draft List of 75 Potential Drinking Water Contaminants Nationwide
Published Date: 4/6/2026
Proposed Rule
Summary
The EPA just shared a draft list of 75 chemicals, 4 groups of substances, and 9 microbes that might show up in our drinking water and could need new safety rules. This affects everyone who drinks public water, and the EPA wants your thoughts by June 5, 2026, before making final decisions. While no new costs are set yet, future rules could impact water providers and communities.
Analyzed Economic Effects
8 provisions identified: 7 benefits, 1 costs, 0 mixed.
Final CCL guides future regulation of 5+ contaminants
The EPA will use the final CCL 6 to prioritize research and data collection and, in a future separate action, will make regulatory determinations on whether to regulate at least five contaminants from the CCL with National Primary Drinking Water Regulations under SDWA section 1412(b)(1)(B)(ii).
PFAS listed as a broad chemical group
EPA proposes listing per- and polyfluoroalkyl substances (PFAS) as a group on the draft CCL 6, using the same structural definition applied in CCL 5 and excluding PFAS that are subject to national drinking water regulations at the time of final CCL 6. The structural definition includes three specific chemical structure patterns described in the document.
Draft CCL 6: 88 contaminants listed
The EPA published a draft Contaminant Candidate List 6 (CCL 6) that includes 75 individual chemicals, 4 chemical groups, and 9 microbes — 88 contaminants in total. These are known or anticipated to occur in public water systems and could be prioritized for future action under the Safe Drinking Water Act.
CCL links to UCMR monitoring (up to 30)
The CCL informs future Unregulated Contaminant Monitoring Rules (UCMR). SDWA section 1445(a)(2) requires EPA to issue a UCMR every five years with a list of no more than 30 unregulated contaminants for public water systems to monitor.
Microplastics listed; major data gaps noted
EPA proposes listing microplastics as a chemical group on the draft CCL 6 and identifies significant data gaps that require research: (1) a health-based definition (characteristics like size, polymer, shape), (2) validated detection technology, (3) understanding microplastics in mixtures, and (4) sources of microplastics contributing to drinking water.
Pharmaceuticals grouped; benchmarks used
EPA proposes listing pharmaceuticals as a chemical group on the draft CCL 6 and used Human Health Benchmarks for Pharmaceuticals (HHB-Rx) to inform screening. For CCL 6 purposes, 'pharmaceuticals' are considered any substances defined as a 'drug' under the Federal Food, Drug, and Cosmetic Act (1938).
No immediate rules for water systems
The draft CCL 6 and the final CCL 6, when published, will not impose any requirements on regulated entities (public water systems). The document is a prioritization and research planning step, not a regulation.
Disinfection byproducts listed as a group
EPA proposes listing disinfection byproducts (DBPs) as one of four chemical groups on the draft CCL 6. The DBP group includes 27 unregulated DBPs — 23 carried from CCL 5 plus 4 additional DBPs (bromochloroacetonitrile, chloral hydrate, chloronitramide anion, and trichloroacetonitrile).
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