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Public Engagements: Potential Revisions of the Microbial and Disinfection Byproducts Rules

EPA is currently seeking public input and information to inform potential regulatory revisions of eight National Primary Drinking Water Regulations (NPDWRs) included in Microbial and Disinfection Byproducts (MDBP) rules following the Six-Year Review 3.

EPA hosted an initial two-day virtual public meeting in October 2020 to solicit input on further improving public health protection from MDBPs in drinking water. Throughout 2021, EPA intends to continue to seek input relevant to any potential rule revisions through a series of public meetings focusing on specific topics identified through public comments and information.

EPA is also currently providing the public with an opportunity to send written input to EPA in the public docket at, Docket ID: EPA-HQ-OW-2020-0486. EPA will consider the data and/or information provided at these meetings, comments submitted to the docket, comments on the Six-Year Review 3 Federal Register notice, and information gathered at other stakeholder engagements in its determination on how to proceed with any potential rule revisions.

Additional questions or comments about the public engagements can be submitted to

Public Engagements Information

Tentative 2021 Public Meeting Series Schedule and Topics - Note: Subject to Change

  • May 20, 2021: Disinfectant Residual Levels and Opportunistic Pathogens (including Legionella)
    • May online meeting registration form 
    • Due to web conferencing size limitations, the number of webinar connections available for the meeting is limited and will be available on a first-come, first-served basis so please register as soon as possible.  All participants must pre-register by May 17, 2021. 
  • June 24, 2021: Regulated and Unregulated Disinfection Byproducts and Consecutive Drinking Water Systems
  • July 14, 2021: Topics TBD
  • August 10, 2021: Topics TBD
  • September 1, 2021: Topics TBD
  • September 29, 2021: Topics TBD
  • November 9, 2021: Topics TBD
  • All meetings will be held from approximately 1:00-4:00pm ET.
  • All meeting are anticipated to be virtual.
  • EPA intends to provide specific meeting materials and other information (e.g., registration, meeting agenda) on this website in advance of each meeting.
  • EPA plans to select future meeting topics based on priority areas identified through current public input. Additional meeting topic examples may include drinking water distribution systems, finished drinking water storage, source water considerations, and potable water reuse. EPA appreciates any additional public input to be provided to the docket as soon as possible to help inform the content, focus, and sequencing of the meetings. Further, in consideration of Executive Order 13992, EPA is currently reviewing additional stakeholder engagement opportunities. More information is available in the public docket at, Docket ID: EPA-HQ-OW-2020-0486.

October 2020 Meeting Information