M/DBP Working Group – Second Meeting

The National Drinking Water Advisory Council (NDWAC) Microbial/Disinfection Byproduct (M/DBP) Rule Revisions Working Group will hold its second meeting (first meeting was held on May 23, 2022) on August 17, 2022 from 11:00 am to 6:00 pm (ET). According to EPA’s announcement the August 17th meeting is “….intended to include a discussion of the current regulatory landscape for the Surface Water Treatment Rules (SWTRs); an inventory of public water systems subject to the SWTRs; and a characterization of problems related to opportunistic pathogens.”

Registration to listen to the virtual meeting of the M/DBP Rule Revisions Working Group is at the link below:

Future meetings of the M/DBP Rule Revisions Working Group are tentatively planned for September 20, November 3, and December 13, 2022.

Under the SDWA as amended in 1996, EPA is required to conduct a review of drinking water regulations every six years, and if appropriate, revise specific regulations. Previous six-year reviews were concluded in 2003 and in 2010. In December 2016, EPA announced the completion of its third review of existing drinking water regulations. EPA determined that eight regulations are candidates for regulatory revision. The eight regulations are chlorite, Cryptosporidium, Giardia lamblia, haloacetic acids (HAA5), heterotrophic bacteria, Legionella, TTHM, and viruses. These constituents are currently regulated under the Long-term 2 Enhanced Surface Water Treatment Rule and the Stage 2 Disinfection Byproduct Rule and are referred to as M/DBP regulations.

In October 2020, and during 2021 EPA held a series of public meetings to obtain input on possible revisions to the eight M/DBP regulations.

In November 2021 EPA published a request that the National Drinking Water Advisory County (NDWAC) “….provide advice and recommendations on key issues related to potential revisions to the following Microbial and Disinfection Byproducts (MDBP) rules: Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules, Surface Water Treatment Rule, Interim Enhanced Surface Water Treatment Rule, and Long-Term 1 Enhanced Surface Water Treatment Rule.” At the same time, EPA requested nominations for an M/DBP Rule Revisions Working Group. The M/DBP Rule Revisions Working Group would make recommendations to the full NDWAC. After reviewing the Working Group’s recommendations, the NDWAC would then submit recommendations of possible M/DBP Rule Revisions to EPA.

EPA intends to propose revised M/DBP regulations by July 2024 and publish the final revised regulations by September 2027.