Drinking Water Requirements for States and Public Water Systems

Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules

Rule Summary

Disinfectants and Disinfection Byproducts Rules

The Stage 1 Disinfectants and Disinfection Byproducts Rule (DBPR) reduces drinking water exposure to disinfection byproducts. The Rule applies to community water systems and non-transient non-community systems, including those serving fewer than 10,000 people that add a disinfectant to the drinking water during any part of the treatment process.

The Stage 2 DBPR strengthens public health protection by tightening compliance monitoring requirements for Trihalomethanes (TTHM) and Haloacetic acids (HAA5). The rule targets public water systems (PWSs) with the greatest risk.

Taken together, the Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules (DBPRs) improve drinking water quality. The rules do this by providing protection from disinfection byproducts. Byproducts, if consumed in excess of EPA's standard over many years, may increase health risks.

Drinking water comes from source water locations such as:

  • Lakes,
  • Rivers,
  • Reservoirs, and
  • Ground water aquifers.

Pathogens, such as GiardiaCryptosporidium, and viruses, are often found in source water and can cause gastrointestinal illness. Illnesses include diarrhea, vomiting, cramps and other health risks. In many cases, water needs to be disinfected to inactivate (or kill) these microbial pathogens. However, disinfectants can react with naturally-occurring materials in the water to form byproducts including:

  • Trihalomethanes (THM),
  • Haloacetic acids (HAA),
  • Chlorite, and
  • Bromate.

EPA has developed the DBPRs to limit exposure to these disinfectant byproducts.

For more information on Chlorine, Chloramine and Chlorine Dioxide, please visit: Basic Information about Disinfectants in Drinking Water website.

Quick Reference Guides for Stage 1 and Stage 2 DBPRs

These documents provide a simple and straightforward description of the rule and critical deadlines. They also detail requirements for drinking water PWSs and states, and information on monitoring requirements.

Additional quick reference materials (e.g., Stage 1 and Stage 2 Comprehensive Disinfectants and Disinfection Byproducts Rules Laboratory Quick Reference Guide)

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Rule History

The Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules (DBPRs) are part of the suite of Microbial and Disinfection Byproducts Rules (MDBPs). MDBPs are a series of interrelated regulations that address risks from microbial pathogens and disinfectants/disinfection byproducts.

The Stage 2 DBPR improves on public health protection by limiting exposure to Disinfection Byproducts (DBPs), specifically:

  • Total trihalomethanes (TTHM), and
  • Five haloacetic acids (HAA5)

DBPs can form in water when disinfectants used to control microbial pathogens combine with naturally occurring materials found in source water. These Rules apply to all Community Water Systems (CWS) and Non-Transient Non-Community Water Systems (NTNCWS) that add/deliver a primary or residual disinfectant, and TNCWs that use chlorine dioxide. This Rule does not apply to water systems that use ultraviolet (UV) light.

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

Occurrence Document

Cost and Technologies

Rulemaking History

Economic Analysis

The basic framework for the Stage 2 DBP Rule was developed by the Stage 2 Microbial/Disinfection Byproduct federal advisory committee. This committee was comprised of state and local government, environmental, public health and water industry stakeholders. The available Stage 2 Microbial/Disinfection Byproduct federal advisory committee materials include:

For additional supporting information related to this rule-making, visit docket number EPA-HQ-OW-2002-0039 at Regulations.gov.

Federal Register Notices

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Additional Resources

  • EPA strongly encourages people to learn more about their drinking water. Your water bill or telephone book's government listings are good starting points for local information.
  • Contact your water utility. EPA requires all community water systems to prepare and deliver an annual consumer confidence report (CCR). It is due for their customers by July 1 of each year. If you have a private water supply, request a copy from a nearby community water system
  • The Consumer Confidence Report (CCR) summarizes information regarding sources used, detected contaminants, compliance and educational information for your water system.

To Reach EPA for More Information

Information about Chloromines in Drinking Water

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EPA provides guidance documents to help states and public water systems (PWSs) implement the Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts (DBP) Rules. The materials below can assist in complying with requirements of the Rules.

Stage 1 and Stage 2 Fact sheets

Initial Distribution System Evaluation Guidance Manuals for the Final Stage 2

Compliance Help for Community Water System Owners and Operators

Compliance Help for Primacy Agencies

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