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Stage 2 Disinfection Byproducts Rule (DBPR)

Stage 2 Overview

The Stage 2 Disinfection Byproducts Rule (DBPR) was promulgated in January 2006 and applies to all community and non-transient non-community (NTNC) water systems that add a primary or residual disinfectant other than ultraviolet light (UV) or deliver water that has been treated with a primary or residual disinfectant other than UV. Systems that purchase disinfected water are included in this rule.

  • The Stage 2 DBPR builds on the existing Stage 1 DBPR and provides increased health protection.
  • Stage 1 monitoring will end when Stage 2 monitoring begins.

Important deadlines are summarized in the following table:

Table 1. Stage 2 DBP Rule Deadlines
Public Water SystemsActions and Deadlines
Schedule numberSubmit IDSE standard monitoring plan, system specific study plan or 40/30 certificationComplete an initial distribution system evaluation (IDSE)Submit IDSE reportBegin Stage 2 compliance monitoring
CWS = Community Water Systems. NTNCWS = Non-Transient Non-Community Water Systems.
State may grant up to an additional two years for systems making capital improvements.
* Systems under 10,000 population that have to monitor for Cryptosporidium may begin Stage 2 compliance monitoring October 1, 2014.
CWS and NTNCWS serving
at least 100,000
CWS and NTNCWS serving 50,000 - 99,99924/1/20073/31/20097/1/200910/1/2012
CWS and NTNCWS serving 10,000 - 49,999310/1/20079/30/20091/1/201010/1/2013
CWS serving fewer than 10,00044/1/20083/31/20107/1/201010/1/2013*
NTNCWS serving fewer than 10,0004N/AN/AN/A10/1/2013*

Stage 2 DBPR Information

Additional Resources

See the following for more Stage 2 DBPR information: