Unregulated Contaminant Monitoring Rule (UCMR)

Current understanding

To be populated as evidence accumulates.

Evidence log

• 2026-10-29 — To direct the Administrator of the Environmental Protection Agency to include certain nanoplastics and microplastics on a certain list of unregulated contaminants published pursuant to the Safe Drinking Water Act, and for other purposes.: 2026 — Introduced House bill would direct EPA to add certain nanoplastics and microplastics to the SDWA unregulated contaminants list, a monitoring step (not an enforceable standard) that would obligate public water systems to sample for these particles under a future UCMR cycle. (novelty: 2)
• 2025-07-23 — Healthy H2O Act: cross-connection with healthy-h2o-act-rural-drinking-water: UCMR captures data at public water systems; the Healthy H2O Act would extend contaminant testing to private wells and small facilities not covered by UCMR. (novelty: 3)
• 2025-11-18 — Safe Hydration is an American Right in Energy Development Act of 2025: 2025 — HR6116 (Safe Hydration is an American Right in Energy Development Act of 2025, introduced) would create a fracking-specific drinking water testing and public reporting regime tied to state UIC primacy — a parallel monitoring pathway distinct from UCMR’s nationwide public water system sampling, but potentially generating overlapping source-water contaminant data. (novelty: 2)
• 2025-11-29 — FRESHER Act of 2025: 2025 — FRESHER Act of 2025 (introduced) would require a DOI study of contamination risks to groundwater and aquifers from mining and oil/gas stormwater runoff, potentially generating source-water contaminant data relevant to UCMR-style monitoring priorities. (novelty: 3)
• 2025-11-18 — Fracturing Responsibility and Awareness of Chemicals Act of 2025: cross-connection with hydraulic-fracturing-sdwa-regulation: Both address EPA authority to identify and regulate chemical contaminants in drinking water sources; FRAC Act disclosure would expand the universe of fracturing-fluid constituents available for UCMR-style monitoring. (novelty: 3)
• 2026-05-20 — Rescission of Regulatory Determinations and Removal of Related Provisions for Four PFAS Substances (PFHxS, PFNA, HFPO-DA (GenX), and the Mixture of These Three PFAS Plus PFBS): cross-connection with pfas-regulation: Rescinding MCLs for PFHxS, PFNA, GenX, and the PFBS-inclusive mixture would leave these substances regulated only through monitoring frameworks like UCMR rather than enforceable drinking water limits. (novelty: 3)
• 2026-07-01 — Revisions To Establish the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) for Public Water Systems: EPA proposed UCMR 6 (proposed rule), requiring public water systems to monitor 7 ultrashort organofluorine compounds (including certain PFAS), 3 pesticide metabolites, and 20 additional organic compounds not currently regulated under NPDWRs; covers CWSs and NTNCWSs serving ≥3,300 people plus a representative sample of smaller systems. (novelty: 3)

Open questions

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