Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules

On this page:

• Rule Summary
• Rule History
• Additional Resources
• Compliance

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 Giardia, Cryptosporidium, 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.

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.

• Stage 1 Disinfection and Disinfection Byproducts Rule: Laboratory Quick Reference Guide (PDF) (2 pp, 543 K, About PDF) EPA 816-F-02-021
• Stage 2 DBPR: A Quick Reference Guide For Schedule 1 Systems (PDF)(2 pp, 123 K, About PDF) EPA816-F-06-001
• Stage 2 DBPR: A Quick Reference Guide For Schedule 2 Systems (PDF)(2 pp, 123 K, About PDF) EPA 816-F-06-002
• Stage 2 DBPR: A Quick Reference Guide For Schedule 3 Systems (PDF)(2 pp, 123 K, About PDF) EPA 816-F-06-003
• Stage 2 DBPR: A Quick Reference Guide For Schedule 4 Systems(PDF)(2 pp, 123 K, About PDF) EPA 816-F-06-004
• Comprehensive Disinfectants and Disinfection Byproducts Rules (Stage 1 and Stage 2) Quick Reference Guide (PDF)(2 pp, 622 K, About PDF) EPA 816-F-10-080

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

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

• Occurrence Assessment for the Final Stage 2 Disinfectants and Disinfection Byproducts (PDF)(209 pp, 3000 K, About PDF) EPA 815-R-05-011, December 2005

Cost and Technologies

• Technologies and Costs Document for the Final Long Term 2 Enhanced Surface Water Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts Rule (PDF)(309 pp, 1000 K, About PDF) EPA 815-R-05-013, December 2005

Rulemaking History

• Stage 2 DBPR Proposal Federal Register Notice (PDF)(68 FR 49548-49681, About PDF) August 18, 2003
• Proposed Stage 2 Disinfectants and Disinfection Byproducts Rule Fact Sheet (PDF)(2 pp, 147 K, About PDF) EPA 815-F-03-006, July 2003

Economic Analysis

• Economic Analysis for the Final Stage 2 Disinfectants and Disinfection Byproducts Rule (PDF)(432 pp, 2000 K, About PDF) EPA 815-R-05-010, Decmeber 2005
• Appendices to the Economic Analysis: Volume I (A-E2) (PDF)
• Appendices to the Economic Analysis: Volume II (F-H) (PDF)
• Appendices to the Economic Analysis: Volume III (I-N) (PDF)

Additional Supporting Information

• Surface Water Analytical Tool (SWAT) Manual(48 pp, 611 K, November 2000, About PDF)
• Water Treatment Plant (WTP) Manual(126 pp, 794 K, May 18 2001, About PDF)
• Empirically Based Models (174 pp,  3.46MB, August 1998, EPA 815-R-98-005, About PDF)

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:

• 2000 Agreement in Principle
• Committee members

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

Federal Register Notices

• Federal Register Notice National Interim Primary Drinking Water Regulations; Control of Trihalomethanes in Drinking Water; Final Rule (pdf) (7.9 MB, November 29, 1979, 44 FR 68624-68707)
• National Primary Drinking Water Regulations: Disinfectants and Disinfection Byproducts Notice of Data Availability; Proposed Rule (PDF)(63 FR 15674-15692, About PDF) March 31, 1998
• National Primary Drinking Water Regulations: Disinfectants and Disinfection Byproducts (PDF)( 63 FR 69390-69476, About PDF) December 16, 1998
• Revisions to the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1DBPR), and Revisions to State Primacy Requirements To Implement the Safe Drinking Water Act (SDWA) Amendments Final Rule (PDF)(66 FR 3770-3780, About PDF) January 16, 2001
• Stakeholder Meetings Concerning the Long-Term 2 Enhanced Surface Water Treatment Rule and Stage 2 Disinfectants and Disinfection Byproducts Rule Proposals; Notice of Public Meetings; Federal Register Notice - September 22, 2003
• Notice of a Public Meeting to Discuss Research Related to the Stage 2 Disinfectants and Disinfection Byproducts Rule Federal Register Notice - December 23, 2004 (PDF)
• National Primary Drinking Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule (PDF)(71 FR 388-493, About PDF) January 2, 2006
• Stage 2 Disinfectants and Disinfection Byproducts Rule Correction (PDF)(71 FR 4644, About PDF) January 27, 2006
• Stage 2 Disinfectants and Disinfection Byproducts Rule Correction (PDF)(71 FR 37168, About PDF) June 29, 2006 
• National Primary Drinking Water Regulations: Minor Correction to Stage 2 Disinfectants and Disinfection Byproducts Rule and Changes in References to Analytical Methods (PDF)(73 FR 67456-67463, About PDF) November 14, 2008

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

• Write:
  EPA’s Water Resource Center (RC-4100T)
  1200 Pennsylvania Avenue, NW
  Washington, DC 20460
  Please specify document(s) requested, or
• Contact the Safe Drinking Water Hotline

Information about Chloramines in Drinking Water

Compliance

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

• Stage 1 Disinfectants and Disinfection Byproducts Rule Fact Sheet (PDF)(4 pp, 18 K, About PDF) 

• Stage 1 Disinfectants and Disinfection Byproducts Rule: What Does it Mean to You? (PDF)(44 pp, 3.4 Mb, About PDF) 

• Fact Sheet: Stage 2 Disinfectants and Disinfection Byproducts Rule (PDF)(4 pp, 40 K, About PDF) EPA 815-F-05-003, December 2005

Initial Distribution System Evaluation Guidance Manuals for the Final Stage 2

• Initial Distribution System Evaluation Guidance Manual For The Final Stage 2 Disinfectants and Disinfection Byproducts Rule (PDF)(434 pp, 814 K, About PDF) EPA 815-B-06-002

• Initial Distribution System Evaluation Guide For Systems Serving Fewer Than 10,000 People, For The Final Stage 2 Disinfectants and Disinfection Byproducts Rule (PDF)(126 pp, 260 K, About PDF) EPA 815-B-06-001

Compliance Help for Community Water System Owners and Operators

Compliance Help for Primacy Agencies