vvEPA
United States
Environmental Protection
Agency
For additional information
on the Stage 2 DBPR
Call the Safe Drinking Water
Hotline at 1-800-426-4791;
visit the EPA web site at
vwwv.epa.gov/safewater/
disinfection/stage2; or
contact yourstate drinking
water representative.
Stage 2 Disinfectants and Disinfection
Byproducts Rule: A Quick Reference
Guide For Schedule 2 Systems
Purpose
General
Description
Utilities
Covered'
Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) 71 FR 388, January 4, 2006,
Vol. 71, No. 2
To increase public health protection by reducing the potential risk of adverse health effects
associated with disinfection byproducts (DBPs) throughout the distribution system. Builds on the
Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) by focusing on monitoring
for and reducing concentrations of two classes of DBPs - TTHM and HAAS - in drinking water.
Stage 2 DBPR requires some systems to complete an Initial Distribution System Evaluation (IDSE) to
characterize DBP levels in their distribution systems and identify locations to monitor DBPs for Stage
2 DBPR compliance. The Stage 2 DBPR bases TTHM and HAAS compliance on a locational running
annual average (LRAA) calculated at each monitoring location.
All community water systems (CWSs) and nontransient noncommunity water systems
(NTNCWSs) that either add a primary or residual disinfectant other than ultraviolet light, or deliver
water that has been treated with a primary or residual disinfectant other than ultraviolet light.
Schedule 2 includes CWSs and NTNCWSs serving 50,000 to 99,999 people OR CWSs and
NTNCWSs that are part of a combined distribution system in which the largest system serves
50,000 to 99,999 people.
* NTNCWSs serving < 10,000 people do not need to complete any of the IDSE options, but must conduct Stage 2 DBPR
compliance monitoring.
Stage 2 DBPR Regulated Contaminants
Regulated Contaminants
Total Trihalomethanes (TTHM)
Chloroform
Bromodichloromethane
Dibromochloromethane
Bromoform
Five Haloacetic Acids (HAAS)
Monochloroacetic acid
Dichloroacetic acid
Trichloroacetic acid
Bromoacetic acid
Dibromoacetic acid
MCLG (mg/L)
0.07
zero
0.06
zero
0.07
zero
0.02
MCL (mg/L)
0.080 LRAA
0.060 LRAA
I DSE Requirements**
IDSE
Option
Standard
Monitoring
System
Specific
Study (SSS)
40/30
Certification *
Very Small
System (VSS)
Waiver*
Description
Standard monitoring is one year of increased monitoring for TTHM and HAAS in addition to the
data being collected under Stage 1 DBPR. These data will be used with Stage 1 DBPR data to
select Stage 2 DBPR TTHM and HAAS compliance monitoring locations. Any system may conduct
standard monitoring to meet the IDSE requirements of the Stage 2 DBPR.
Systems that have extensive TTHM and HAAS data (including Stage 1 DBPR compliance data) or
technical expertise to prepare a hydraulic model may choose to conduct a system specific study
to select Stage 2 DBPR compliance monitoring locations.
The term "40/30" refers to a system that during a specific time period has all individual Stage 1
DBPR compliance samples less than or equal to 0.040 mg/L for TTHM and 0.030 mg/L for HAAS
and has no monitoring violations during the same time period. These systems have no IDSE
monitoring requirements, but will still need to conduct Stage 2 DBPR compliance monitoring.
Systems that serve fewer than 500 people and have eligible TTHM and HAAS data can qualify for a
VSS Waiver and would not be required to conduct IDSE monitoring. These systems have no IDSE
monitoring requirements, but will still need to conduct Stage 2 DBPR compliance monitoring.
EPA has developed several tools to assist systems with complying with the Stage 2 DBPR IDSE requirements.
These materials can be downloaded at www.epa.gov/safewater/disinfection/stage2.
** NTNCWSs serving < 10,000 people do not need to complete any of the IDSE options.
t Systems that are notified by EPA or the state their VSS waiver or 40/30 certification has not been approved will need to
complete Standard Monitoring or System Specific Study.
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Compliance with Stage 2 DBPR MCLs (Routine Monitoring)
Source
Water Type
Subpart H
Ground Water
Population Size
Category
<500
500-3,300
3,301-9,999
10,000-49,999
50,000-249,999
250,000-999,999
1,000,000-4,999,999
>5,000,000
<500
500-9,999
10,000-99,999
100,000-499,999
>500,000
Monitoring
Frequency 1
per year
per quarter
per quarter
per year
per quarter
Total Distribution System Monitoring
Locations Per Monitoring Period2
2
2
2
4
8
12
16
20
2
2
4
6
8
Operational Evaluation
Systems must begin complying with the operational evaluation provision of the Stage 2 DBPR.
1 All systems must monitor during month of highest DBF concentrations.
2 Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for subpart H systems serving 500-3,300. Systems on
annual monitoring and subpart H systems serving 500-3,300 are required to take individual TTHM and HAAS samples (instead of a dual sample set) at the locations with
the highest TTHM and HAAS concentrations, respectively. If monitoring annually, only one location with a dual sample set per monitoring period is needed if highest
TTHM and HAAS concentrations occur at the same location, and month.
Critical Deadlines and Requirements
For Drinking Water Systems (Schedule 2)
January 4, 2006
April 1, 2007
April 1, 2008
March 31, 2009
July 1, 2009
April 1, 2009
October 1, 2012
July 2013
Systems serving fewer than 500 people that have TTHM and HAAS compliance data qualify for a VSS Waiver from conducting an
IDSE, unless informed otherwise by U.S. EPA or state primacy agency.
Systems that do not receive a VSS Waiver must submit to the U.S EPA or state primacy agency either a:
> Standard monitoring plan,
> System specific study plan, or
> 40/30 certification.
Systems conducting standard monitoring or SSS begin collecting samples in accordance with their approved plan.
No later than this date, systems conducting standard monitoring or a SSS complete their monitoring or study.
No later than this date, systems conducting standard monitoring or a SSS must submit their IDSE report.
Consecutive systems must begin monitoring for chlorine or chloramines as specified under the Stage 1 DBPR
No later than this date, systems must:
> Complete their Stage 2 DBPR Compliance Monitoring Plan (Systems serving more than 3,300 people must submit their
Monitoring Plan to the state.)*
> Begin complying with monitoring requirements of the Stage 2 DBPR.*
Systems must begin complying with rule requirements to determine compliance with the operational evaluation levels for TTHMs
and HAASs.
For States
January - June
2006
March 31, 2008
October 4, 2007
January 4, 2008
September 30, 2009
January 4, 2010
States are encouraged to inform systems serving fewer than 500 people and do not qualify for a VSS Waiver from the IDSE
requirements should begin complying with standard monitoring requirements.
States must approve the system's standard monitoring plan, 40/30 certification, or system specific study plan or notify the
system that the state has not completed its review.
States are encouraged to submit final primacy applications or extension requests to EPA.
Final primacy applications must be submitted to EPA, unless granted an extension.
States must approve the system's IDSE report or notify the system that the state has not completed its review of the IDSE report.
Final primacy revision applications from states with approved 2-year extensions agreements must be submitted to EPA.
* A monitoring plan is not required if the IDSE report includes all information required in the monitoring plan.
t States may allow up to an additional 24 months for compliance with MCLs for systems requiring capital improvements.
Office of Water (4606)
EPA816-F-06-002
vwwv.epa.gov/safewater
June 2006
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