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Stage 2 Disinfection Byproducts Rule (DBPR)
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 Systems Actions and Deadlines
Schedule number Submit IDSE standard monitoring plan, system specific study plan or 40/30 certification Complete an initial distribution system evaluation (IDSE) Submit IDSE report Begin 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
1 10/1/2006 9/30/2008 1/1/2009 4/1/2012
CWS and NTNCWS serving 50,000 ‑ 99,999 2 4/1/2007 3/31/2009 7/1/2009 10/1/2012
CWS and NTNCWS serving 10,000 ‑ 49,999 3 10/1/2007 9/30/2009 1/1/2010 10/1/2013
CWS serving fewer than 10,000 4 4/1/2008 3/31/2010 7/1/2010 10/1/2013*
NTNCWS serving fewer than 10,000 4 N/A N/A N/A 10/1/2013*


Stage 2 DBPR Information

Additional Resources
See the following for more Stage 2 DBPR information: