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EPA Proposes UCMR 6 - 30 Contaminants Added to Drinking Water Monitoring

EPA proposed the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) on July 1, 2026, requiring public water systems (PWSs) to collect national occurrence data for 30 contaminants not currently subject to federal drinking water standards. The proposal covers seven ultrashort organofluorine compounds (including certain PFAS (Per- and Polyfluoroalkyl Substances)), three pesticide metabolites, 13 semivolatile organic compounds (SVOCs), and seven purgeable organic compounds. Here is what the proposed rule covers and what it means for consultants working near drinking water sources.

What UCMR 6 Proposes

The Unregulated Contaminant Monitoring Rule (UCMR) program operates under the Safe Drinking Water Act (SDWA) and is EPA’s primary mechanism for building national occurrence data on contaminants before deciding whether to regulate them. UCMR 6 would be the sixth iteration of this program.

The proposed contaminant groups are:

  • Ultrashort-chain organofluorines: Seven compounds, including certain PFAS. These are shorter-chain variants that have received less regulatory attention than PFOA and PFOS but are increasingly detected in source water.
  • Pesticide metabolites: Three breakdown products of parent pesticides. Monitoring targets metabolites specifically because parent compound data often underestimates actual exposure.
  • Semivolatile organic compounds (SVOCs): Thirteen compounds. SVOCs include a broad range of industrial chemicals and combustion byproducts.
  • Purgeable organic compounds: Seven compounds analyzed by purge-and-trap methods, overlapping with the volatile organic compound (VOC) analytical universe.

EPA notes that monitoring is subject to the availability of appropriations. The proposal does not establish maximum contaminant levels (MCLs) or cleanup standards for any of these compounds - UCMR data collection precedes that regulatory step.

How This Affects Ohio Site Work

VAP and BUSTR Sites Near Public Water Supplies

UCMR 6 does not change Ohio’s Voluntary Action Program (VAP) or BUSTR cleanup standards directly. However, occurrence data collected under UCMR programs has historically informed EPA’s decision to regulate contaminants, which then flows into state cleanup standards. If UCMR 6 data shows widespread detection of ultrashort PFAS or specific SVOCs in Ohio public water supplies, that creates pressure for future standard-setting at both the federal and state level.

PFAS Site Investigations

If you are conducting PFAS investigations near public water supply intakes, the ultrashort-chain compounds targeted by UCMR 6 are worth flagging now. Analytical methods for ultrashort organofluorines are still developing, and your laboratory should confirm method capability before sampling. The PFAS sampling best practices guide covers equipment restrictions and decontamination protocols relevant to any PFAS-related field work.

Drinking Water Pathway Analysis

For risk assessments that evaluate the drinking water pathway, UCMR 6 data - once collected - will eventually populate EPA’s national occurrence database. That data can support or challenge assumptions about background concentrations in source water. Watch for how EPA uses UCMR 6 results in future RSL (Regional Screening Level) or MCL rulemakings.

What to Watch

This is a proposed rule as of July 1, 2026. EPA will accept public comments before finalizing. The monitoring schedule, specific analytical methods, and which PWSs are required to participate will be confirmed in the final rule. Check the Federal Register docket for the comment deadline and any subsequent revisions. We will update this post as the rulemaking progresses.

Bottom Line

UCMR 6 does not set new cleanup numbers, but it targets 30 contaminants - including ultrashort PFAS and new SVOC and pesticide metabolite groups - that could drive future MCL and screening level changes. If your site work involves drinking water pathways or PFAS, track this rulemaking. For current PFAS drinking water standards applicable to Ohio sites, see our Ohio PFAS standards and state-by-state PFAS comparison pages.