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March 2021 – Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 5) for Public Water Systems (PWS) and Announcement of Public Meeting – Additional PFAS compounds to be monitored

Revisions to UCMR 5 for Public Water Systems and Announcement of Public Meeting – Additional PFAS to be Monitored

On March 11, 2021, US EPA issued a notice of proposed rule and notice of public meeting in the Federal Register regarding unregulated contaminants it proposes to regulate under the Unregulated Contaminant Monitoring Rule (UCMR 5). This proposal includes public meetings. The comments to the proposed rule are due by May 10, 2021. Additionally, the announcement states that in order for comments to be best assured of consideration, comments are to be received by April 12, 2021. The primary list of compounds under consideration are listed on Table 1.

The US EPA asserts that this proposal is intended to fulfill the “EPA’s 2019 Per- and Polyfluoroalkyl Substances (PFAS) Action Plan,” and the National Defense Authorization Act (NDAA) of 2019. The list of compounds to be monitored (29 PFAS and lithium) referenced on Table 1 is the primary focus. Additional compounds evaluated, include Legionella pneumophila; four haloacetonitriles (dichloroacetonitrile, dibromoacetonitrile, trichloroacetonitrile and bromochloroacetonitrile); 1,2,3 trichloropropane; and total organic fluorine (TOF).

The intended population of public water systems (PWSs) monitored applies to a population of communities with 3,300 and up to 10,000 people. The monitoring also includes a representative sample of smaller water systems. The proposed timeline for the UCMR 5 activities is as follows:

2022: Pre-sampling Activity by US EPA

  • Manage Lab Approval Program
  • Organize agreements and state monitoring plans
  • Begin PWS Safe Drinking Water Accession and Review System (SDWARS) registration/inventory
  • Review groundwater representative monitoring plan (GWRMP) submittals
  • Conduct outreach/trainings

2023 to 2025: Sampling period

  • All large systems serving more than 10,000 people
  • All small systems serving between 3,300 and 10,000
  • 800 small systems serving fewer than 3,300 people

2026: Post-sampling activities

  • Complete resampling if necessary
  • Conclude data reporting
  • Complete upload of UCMR 5 data to National Contaminant Occurrence Database (NCOD)

US EPA will be offering a virtual meeting twice during the comment period. The details of those virtual meetings can be obtained by visiting:


1EPA Method 533 [Solid phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS)], (US EPA, ).

2EPA Method 537.1 Version 2.0 [Solid phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS)] (US EPA, 2020b).

3EPA Method 200.7 [Inductively coupled plasma-atomic emission spectrometry (ICP–AES)] (US EPA, 1994).

4Standard Methods (SM) 3120 B (SM, 2017) or SM 3120 B–99, (SM Online, 1999).

5ASTM International (ASTM) D1976–20, (ASTM, 2020).

Ref: Federal Register / Vol. 86, No. 46 / Thursday, March 11, 2021 / Proposed Rules

Gary Yakub


David Thal

David Thal, CQA, CEAC, CFS

Principal Chemist