Jump to main content or area navigation.

Contact Us

Water: Stage 2 DBP Rule

Stage 2 Rule

Welcome to the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBP rule) page. On this site you will find links to the rule, fact sheets as well as general information about the history of the rulemaking.

Stage 2 DBP Rule Federal Register Notices and Fact Sheets

The Stage 2 DBP rule is one part of the Microbial and Disinfection Byproducts Rules (MDBPs), which are a set of interrelated regulations that address risks from microbial pathogens and disinfectants/disinfection byproducts. The Stage 2 DBP rule focuses on public health protection by limiting exposure to DBPs, specifically total trihalomethanes (TTHM) and five haloacetic acids (HAA5), which can form in water through disinfectants used to control microbial pathogens. This rule will apply to all community water systems and nontransient noncommunity water systems that add a primary or residual disinfectant other than ultraviolet (UV) light or deliver water that has been disinfected by a primary or residual disinfectant other than UV.

Federal Register Notices

Quick Reference Guide to Stage 2 DBP Rule

This document provides a simple and straightforward description of the rule, critical deadlines and requirements for drinking water systems and states, and information on monitoring requirements.

Questions and Answers

Stage 2 DBP Rule Supporting Documents

The following documents were developed to support the final rule-making.

Rulemaking History

Stage 2 DBP Rule Proposal Federal Register Notice

Stake Holder Meetings

Agreement in Principle

The basic framework for the rule was developed by the Stage 2 Microbial/Disinfection Byproductfederal advisory committee which was comprised of state and local government, environmental, public health and water industry stakeholders.


Jump to main content.