United States
Environmental Protection
Agency
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r
Comprehensive Disinfectants and
Disinfection Byproducts Rules (Stage 1
and Stage 2): Quick Reference Guide
Overview of the Rules
Titles*
Purpose
General
Description
Utilities
Covered
>• Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) 63 FR 69390,
December 16, 1998, Vol. 63, No. 241
> Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) 71 FR 388, January 4,
2006, Vol.71, No. 2
Improve public health protection by reducing exposure to disinfection byproducts. Some disinfectants
and disinfection byproducts (DBPs) have been shown to cause cancer and reproductive effects in
lab animals and suggested bladder cancer and reproductive effects in humans.
The DBPRs require public water systems (PWSs) to:
> Comply with established maximum contaminant levels (MCLs) and operational evaluation
levels (OELs) for DBPs, and maximum residual disinfection levels (MRDLs) for disinfectant
residuals.
^ Conduct an initial evaluation of their distribution system.
In addition, PWSs using conventional filtration are required to remove specific percentages of
organic material that may react to form DBPs through the implementation of a treatment technique.
The DBPRs apply to all sizes of community water systems (CWSs) and nontransient noncommunity
water systems (NTNCWSs) that add a disinfectant other than ultraviolet (UV) light or deliver
disinfected water, and transient noncommunity water systems (TNCWSs) that add chlorine dioxide.
This document provides a summary of federal drinking water requirements; to ensure full compliance, please
consult the federal regulations at 40 CFR 141 and any approved state requirements.
Overview
This table shows how the requirements for the Stage 2 DBPR build on the existing requirements established in
the Stage 1 DBPR. For more information on changes in monitoring requirements, see Table 1.
Coverage
TTHM &
HAAS MCL
Compliance
Regulated
Contaminants
& Disinfectants
Operational
Evaluation
All CWSs and NTNCWSs that add
disinfectant other than UV light and
TNCWSs that treat with chlorine dioxide.
Consecutive systems that deliver water
treated with a disinfectant other than UV
light.
MCL compliance is calculated using the
running annual average (RAA) of all
samples from all monitoring locations
across the system.
MCL compliance is calculated using the
locational RAA (LRAA) for each monitoring
location in the distribution system.
Stage 1
DBPR
S
^
Stage 2
DBPR
S
S
S
Contaminants
Total Trihalomethanes (TTHM)
5 Haloacetic Acids (HAAS)
Bromate
Chlorite
S
/;
/;
/;
s
s
Regulated under
Stage 1 DBPR1
Regulated under
Stage 1 DBPR
Disinfectants
Chlorine/chloramines
Chlorine dioxide
If an operational evaluation level (OEL)
is exceeded, systems must evaluate
practices and identify DBP mitigation
actions.
s
£
Regulated under
Stage 1 DBPR
Regulated under
Stage 1 DBPR
s
For More
Info:
See Table 3
and Table 4.
See Table 2.
See Table 5.
1. A new analytical method for bromate was approved with the Stage 2 DBPR.
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Stage 1 DBPR
Stage 2 DBPR
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Number of Samples
Based on source water type, population, and number
of treatment plants or wells.
Based on source water type and population.
Sample Locations
At location of maximum residence time.1
Based on Initial Distribution System Evaluation
(IDSE) requirements.2
Compliance Calculation
RAA must not exceed the MCL for TTHM or HAAS.
LRAA must not exceed the MCL for TTHM or HAAS.
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Eligibility
TTHM/HAA5
All systems need TTHM RAA < 0.040 mg/L and HAAS
< 0.030 mg/L. Subpart H systems also need source
water TOC RAA at location prior to treatment < 4.0
mg/L.3-4
The Stage 2 DBPR left eligibility unchanged but
specifies that Subpart H systems must take source
water TOC samples every 30 days. Subpart H
systems on reduced monitoring must take source
water TOC samples every 90 days to qualify for
reduced monitoring.
Bromate5
Source water bromide RAA < 0.05 mg/L.
With the Stage 2 DBPR specified entry point to
distribution system bromate RAA < 0.0025 mg/L.
1Subpart H systems serving >_ 10,000 must have at least 25 percent of samples at the location of maximum residence time; the remaining samples
must be representative of average residence time.
2AII systems are required to satisfy their IDSE requirement by July 10, 2010.
3Subpart H systems are water systems that use surface water or ground water under the direct influence of surface water (GWUDI).
4Ground water systems serving < 10,000 must meet these RAA for 2 years; can also qualify for reduced monitoring if the TTHM RAA is < 0.020 mg/L
and a HAAS RAA < 0.015 mg/L for 1 year.
5A new analytical method for bromate was established with the Stage 2 DBPR.
Table 2. Regulated Contaminants and Disinfectants
Regulated Contaminants
TTHM
Chloroform
Bromodichloromethane
Dibromochloromethane
Bromoform
HAAS
Monochloroacetic acid
Dichloroacetic acid
Trichloroacetic acid
Bromoacetic acid
Dibromoacetic acid
Bromate (plants that use ozone)1
Chlorite (plants that use chlorine
dioxide)
Regulated Disinfectants
Chlorine
Chloramines
Chlorine dioxide
Stage 1 DBPR
MCL (mg/L)
0.080
0.060
0.010
1.0
MRDL3 (mg/L)
4.0asCI2
4.0asCI2
0.8
MCLG (mg/L)
-
Zero
0.06
Zero
Zero
0.3
-
Zero
0.8
MRDLG3 (mg/L)
4
4
0.8
Stage 2 DBPR
MCL (mg/L)
Unchanged2
Unchanged2
Unchanged2
Unchanged2
MRDL (mg/L)
Unchanged2
Unchanged2
Unchanged2
MCLG (mg/L)
0.07
Unchanged2
Unchanged2
Unchanged2
0.07
Unchanged2
0.2
-
Unchanged2
Unchanged2
MRDLG (mg/L)
Unchanged2
Unchanged2
Unchanged2
1A new analytical method for bromate was established with the Stage 2 DBPR.
2Stage 2 DBPR did not revise the MCL or MRDL for this contaminant/disinfectant.
3Stage 1 DBPR included MRDLs and MRDLGs for disinfectants, which are similar to MCLs and MCLGs.
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Table 3. Compliance Determination
TTHM/HAA5
Bromate1
Chlorite
Chorine dioxide
Chlorine/chloramines
DBP precursors
(TOC sample set)*
Stage 1 DBPR
RAA
RAA
Daily/follow-up monitoring
Daily/follow-up monitoring
RAA
Monthly for TOC and alkalinity
Stage 2 DBPR
LRAA
Unchanged2
Unchanged2
Unchanged2
Unchanged2
Every 30 days for TOC and alkalinity
1A new analytical method for bromate was established with the Stage 2 DBPR.
2Stage 2 DBPR did not change the compliance requirements for this contaminant/disinfectant.
*TOC sample set is comprised of source water alkalinity, source water TOC, and treated TOC.
Table 4. Compliance with MCLs and MRDLs (Routine Monitoring)
Contaminant/
Disinfectant
TTHM/HAA5
Bromate3
Chlorite
Chlorine dixoide
Chorine/
Chloramines
DBP precursors
(TOC sample
set)*
Coverage
Source
Water
Subpart H
Ground
water
Population
<500
500 - 3,300
3,301 -9,999
10,000-49,000
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
Systems that use ozone as a
disinfectant
Systems that use chlorine dioxide
as a disinfectant
Systems that use chlorine dioxide
as a disinfectant
All systems
Systems that use conventional
filtration
Stage 1 DBPR
Monitoring
Frequency
Per year2
Per quarter
Per year2
Per quarter
Monthly
Daily (at
entrance to
distribution
system);
monthly (in
distribution
system)
Daily
Total Distribution
System Monitoring
Locations
1 per treatment plant
1 per treatment plant
4 per treatment plant
1 per treatment plant
1 at entry point to
distribution system
1 at entry point to
distribution system; 3 in
distribution system
1 at entry point to
distribution system
Same location and frequency as Total
Coliform Rule (TCR) sampling
Monthly
1 per source water
source
Stage 2 DBPR
Monitoring
Frequency1
Per year2
Per quarter
Per year2
Per quarter
Total Distribution
System Monitoring
Locations
2
2
4
8
12
16
20
2
4
6
8
Unchanged4
Unchanged4
Unchanged4
Unchanged4
Unchanged4
1AII systems must monitor during the month of highest DBP concentrations. Systems on quarterly monitoring, except Subpart H systems serving
500 - 3,300, must take dual sample sets every 90 days at each monitoring location. 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 the highest TTHM and
HAAS concentrations occur at the same location and in the same month.
2Ground water systems serving < 10,000 and Subpart H systems serving < 500 must increase monitoring to quarterly if an MCL is exceeded.
3A new analytical method for bromate was established with the Stage 2 DBPR.
4Stage 2 DBPR did not revise the monitoring frequency or location requirements for this contaminant/disinfectant.
*TOC sample set is comprised of source water alkalinity, source water TOC, and treated TOC.
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Table 5. Operational Evaluation Levels (OELs)
Applies to:
Purpose of
establishing OELs:
OEL calculations:
OELs are exceeded:
If an OEL is
exceeded, a system
must:
The operational
evaluation must
include:
OEL requirements
take effect:
All systems subject to Stage 2 DBPR monitoring requirements that conduct compliance
monitoring and collect samples quarterly.
To reduce peaks in DBP levels and exposure to high DBP levels.
^ Calculated for both TTHMs and HAASs at each monitoring location using Stage 2
DBPR compliance monitoring results.
^ OEL is determined by the sum of the two previous quarter's TTHM or HAAS result
plus twice the current quarter's TTHM or HAAS result at that location, divided by four.
> OEL=(Q1 +Q2 + 2Q3)/4
During any quarter in which the OEL is greater than the TTHM or HAAS MCL.
^- Conduct an operational evaluation.
^- Submit a written report of the evaluation to the state no later than 90 days after being
notified of the analytical results that caused the exceedance(s).
^- Keep a copy of the operational evaluation report and make it publically available
upon request.
^- An examination of the treatment and distribution systems' operational practices that
may contribute to TTHM and HAAS formation.
^ Steps to minimize future exceedances.
When the system begins compliance monitoring for the Stage 2 DBPR.
«
I
For additional information
on the DBPRs:
Call the Safe Drinking
Water Hotline at 1-800-
426-4791; visit the EPA
web site at http://water.
epa.gov/drink: or contact
your state drinking water
representative.
Table 6. Standard Monitoring Compliance Dates
If You are a System Serving:
At least 1 00,000 people or part of a
combined distribution system (CDS) serving
at least 100,000 people.
50,000 to 99,999 people or part of a CDS
serving 50,000 to 99,999 people.
1 0,000 to 49,999 people or part of a CDS
serving 10,000 to 49,999 people.
Less than 10,000 people or part of a CDS
serving less than 10,000 people.
Schedule1
1
2
3
4
Begin LRAA TTHM & HAAS
Monitoring By:
April 1,2012
October 1, 2012
October 1, 2013
October 1, 201 32
1Your schedule is determined by the largest system in your CDS.
2Systems not conducting Cryptosporidium monitoring under Long Term 2 Enhanced Surface Water Treatment
Rule (LT2ESWTR) must begin LRAATTHM/HAA5 monitoring by this date. Systems conducting Cryptosporidium
monitoring under LT2ESWTR must begin LRAATTHM/HAA5 monitoring by October 1, 2014.
Table 7. TOC Removal
Subpart H systems that use conventional filtration treatment are required to remove specific percentages of
organic materials, measured as total organic carbon (TOC), that may react with disinfectants to form DBFs.
Removal must be achieved through a treatment technique (enhanced coagulation or enhanced softening) unless
a system meets alternative criteria. Systems practicing softening must meet TOC removal requirements for
source water alkalinity greater than 120 mg/L CaC03.
Source Water TOC
(mg/L)
> 2.0 to 4.0
> 4.0 to 8.0
>8.0
Source Water Alkalinity, mg/L as CaCO3
0-60
35.0%
45.0%
50.0%
> 60 to 120
25.0%
35.0%
40.0%
> 120
15.0%
25.0%
30.0%
Office of Water (4606M)
EPA 816-F-10-080
http://water.epa.gov/drink
August 2010
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