Microbial and disinfection byproducts regulations: Paving the way for efficient compliance

The drinking water industry has spent the past several years preparing for significant regulatory changes, but another major update is already on the horizon. The U.S. Environmental Protection Agency (EPA) is expected to propose revisions to the Microbial and Disinfection Byproducts (MDBP) regulations in 2027, with final regulations anticipated in 2028 and compliance expected by 2031.

A recent article published in Water Online, “Microbial and Disinfection Byproducts Regulations: Paving the Way for Efficient Compliance,” by Carollo’s Alan Roberson, Caroline Russell, and Kathryn Lopez, outlines what utilities can expect and why planning now can make future compliance much easier.

What Are the Proposed MDBP Regulation Changes?

Disinfection is essential for protecting public health, but it can also produce unintended chemical compounds called disinfection byproducts (DBPs) when disinfectants such as chlorine react with naturally occurring organic matter in water.

While the EPA is still developing the proposed revisions, the agency is expected to build on recommendations from the National Drinking Water Advisory Council (NDWAC). According to the authors, the initial focus is likely to include secondary disinfectant residuals, compliance monitoring, and storage tank inspections.

Rather than introducing entirely new treatment requirements, many of the proposed changes are expected to place greater emphasis on how utilities monitor and manage their distribution systems.

What Water Utilities Should Watch for as Regulations Change

The article highlights several potential changes that utilities should begin evaluating now.

The EPA may establish new numerical ranges for secondary disinfectant residuals and revise how compliance is measured. The agency is also considering additional operational requirements when systems repeatedly experience low disinfectant residuals at the same sampling locations, even if overall compliance targets are met.

For systems using chloramines, future regulations could require formal nitrification action plans along with additional monitoring during chlorine conversion periods.

Although these proposals are still under development, they point toward a future with more proactive distribution system management and expanded operational oversight.

Preparing for Future MDBP Compliance

The authors emphasize that utilities do not need to wait for the final rule before taking action.

Reviewing current disinfectant residual performance, identifying areas where low residuals or DBP formation may occur, evaluating staffing and sampling capacity, and exploring modeling tools can all help utilities understand how future requirements may affect their systems.

Taking these steps now can help reduce future compliance challenges while supporting more efficient operational and capital planning.

Read the full article in Water Online to learn more about the anticipated MDBP regulatory changes and practical steps utilities can take to prepare.