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IDSE Standard Monitoring Factsheet
WHAT Is THE STAGE 2 DBPR?
The U.S. Environmental Protection Agency (EPA) published the Stage 2 Disinfectants and Disinfection
Byproducts Rule (Stage 2 DBPR) on January 4, 2006. The Stage 2 DBPR builds on existing regulations by
requiring water systems to meet disinfection byproduct (DBP) maximum contaminant levels (MCLs) at each
monitoring site in the distribution system to better protect public health.
WHAT Is THE IDSE PROVISION OF THE STAGE 2 DBPR?
The Stage 2 DBPR includes a provision requiring all community water systems (CWS) and only nontransient
noncommunity water systems (NTNCWS) serving more than 10,000 people to conduct an initial distribution
system evaluation (IDSE). NTNCWS serving less than 10,000 are exempted from IDSE requirements, but will
need to comply with the Stage 2 DBPR compliance monitoring requirements. The goal of the IDSE is to
characterize the distribution system and identify monitoring sites where customers may be exposed to high
levels of total trihalomethanes (TTHM) and haloacetic acids (HAAS). There are four ways to comply with the
IDSE requirements: Standard Monitoring, System Specific Study, 40/30 Certification (40/30), and Very Small
System (VSS) Waiver. The Standard Monitoring option requires the system to collect 1 year of TTHM and HAAS
data at a specified frequency and locations to characterize TTHM and HAAS levels in the distribution system. In
addition to this data, the system must use available Stage 1 DBPR compliance data to determine the best
locations for Stage 2 DBPR compliance monitoring. Any system may conduct Standard Monitoring to meet the
IDSE requirements of the Stage 2 DBPR. This factsheet only provides information regarding the Standard
Monitoring option.
STANDARD MONITORING REQUIREMENTS
Systems opting to conduct Standard Monitoring will need to:
• Step 1: Prepare and submit a Standard Monitoring Plan by the date specified in Table 1 (below).
• Step 2: Conduct one year of Standard Monitoring in the distribution system.
• Step 3: Prepare and submit the IDSE Report.
• Step 4: Prepare a Stage 2 DBPR compliance monitoring plan.
Table 1: Standard Monitoring Compliance Dates
Standard Complete _ , . .___ Begin
., . . c , , . ! . . .. . ... ... , , Submit IDSE ,.
If you are a system serving: Schedule: Monitoring Plan Standard Compliance
Due Date: Monitoring by: Monitoring by:
At least 100,000 people or part of
a combined distribution system
serving at least 100,000 people
50,000 to 99,999 people or part of
a combined distribution system
serving 50,000 to 99,999 people
10,000 to 49,999 people or part of
a combined distribution system
serving 10,000 to 49,999 people
Less than 10,000 or part of a
combined distribution system
serving less than 10,000
Schedule 1
Schedule 2
Schedule 3
Schedule 4
October 1 , 2006
April 1,2007
October 1 , 2007
April 1,2008
September 30, 2008
March 31 , 2009
September 30, 2009
March 31, 2010
January 1 , 2009
July 1 , 2009
January 1, 2010
July 1,2010
April!, 2012
October 1,201 2
October 1 , 201 3
October 1,201 3 2
1 Your schedule is defined by the largest system in your combined distribution system.
2 Systems not conducting Cryptosporidium monitoring under 40 CFR 141.701 (a)(4) must begin Stage 2 DBPR compliance monitoring by this date. Systems
conducting Cryptosporidium monitoring under 40 CFR 141.701 (a)(4) or 141.701 (a)(6) must begin Stage 2 DBPR compliance monitoring by October 1, 2014.
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STEP 1: PREPARE a SUBMIT STANDARD MONITORING PLAN
THE REQUIRED ELEMENTS OF A STANDARD MONITORING PLAN ARE:
• Population served by your system.
• System Type: Subpart H (surface water or ground water under the direct influence of surface water) or
Ground Water.
H Distribution System Schematic showing:
• Entry points.
• Sources.
• Locations and dates of all projected standard monitoring and Stage 1 DBPR compliance samples.
• Locations of tanks, booster chlorination and water mains.
• Justification of Standard Monitoring site selection and a summary of additional data used to support
standard monitoring site selection.
HOW TO SELECT STANDARD MONITORING SITES - Your standard monitoring
plan must include the locations and dates for one year of monitoring. The
monitoring frequency and number of sites required is based on your system's
source water and population as shown in Tables 2. These sites are in addition
to your Stage 1 DBPR compliance monitoring sites; therefore, you may not
use Stage 1 DBPR monitoring locations as standard monitoring sites. In
addition, the system will need to determine and monitor during the peak
historical month.
Peak Historical Month:
Is the month with the
highest TTHM or the highest
HAAS levels or the warmest
water temperature. It is
meant to represent the
"worst case" scenario for
DBP formation.
Table 2: Standard Monitoring Requirements for Subpart H Systems
Source
Type
Population Size Category
Monitorini
Periods and
Frequency of
Sampling
Distribution System Monitoring Locations 1
Total per Near | Average
monitoring
period Points2 I Time
Locations Locations
s
u
b
P
a
r
t
H
G
r
o
u
n
d
<500 consecutive
<500 non-consecutive
500-3,300 consecutive
500-3,300 non-consecutive
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 consecutive
<500 non-consecutive
500-9,999
10,000-99,999
100,000-499,999
• 500,000
one (during peak
historical month)
four
(every 90 days)
six
(every 60 days)
one (during peak
historical month)
Four
(every 90 days)
2
2
2
2
4
8
16
24
32
40
2
2
2
6
8
12
1
1
-
-
1
3
4
6
8
1
-
-
1
1
2
-
-
-
-
1
2
4
6
8
10
-
-
-
1
1
2
1
1
1
1
2
3
5
8
10
12
1
1
1
2
3
4
-
1
-
1
1
2
4
6
8
10
-
1
1
2
3
4
1 When choosing sites consider TTHM and HAAS Levels, Residence Time, Water Age, Disinfectant Residual, Geographic Coverage of
Distribution System, and Hydraulic Representation.
2 Near Entry Points: If you have more sites than required: choose entry points with the highest flows. If you have fewer sites than
required: replace additional sites with TTHM and HAAS sites.
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HOW TO SUBMIT A STANDARD MONITORING PLAN:
Submit Electronically:
Go To: www.epa.gov/safewater/disinfection/tools
and access the IDSE Tool, Plan/Report Entry.
Create an electronic Standard Monitoring Plan
using the template provided in the IDSE Tool.
Attach schematic and additional information.
Submit by the Due Date presented in Table 1
(above).
Keep the confirmation number and copy of your
plan for your files.
Submit By Mail:
Create a Standard Monitoring Plan. A
template can be found in the IDSE Guidance
Manual.
Attach schematic and additional information.
Mail submission to the IPMC:
US EPA-IPMC
PO Box 98
Dayton, OH 45401-0098
STEP 2: CONDUCT STANDARD MONITORING
Once EPA or the state approves your plan, you must conduct standard monitoring at each of the monitoring
locations and dates listed in your standard monitoring plan. If you deviate from the approved plan for any
reason, you must include an explanation for the deviation in your IDSE Report. During each sample event, you
must collect a dual sample set at each location. A dual sample set consists of analyzing one sample for TTHM
and another one for HAAS. You must use a certified laboratory and EPA-approved methods for analysis of your
TTHM and HAAS samples.
STEP 3: PREPARE AND SUBMIT IDSE REPORT
The required elements of the IDSE Report are:
• TTHM and HAAS analytical results from all Stage 1 DBPR and Standard Monitoring conducted during the
period of standard monitoring, provided in a tabular or spreadsheet format.
• Explanation of any deviations from the approved standard monitoring plan.
• Recommendations and justification for Stage 2 DBPR compliance monitoring sites and dates.
• If the following information changed from the approved standard monitoring plan, also include:
• Distribution system schematic.
• Population served by the system.
• System type (subpart H or ground water).
HOW TO SELECT STAGE 2 DBPR COMPLIANCE MONITORING SITES AND DATES - You will use results from
standard monitoring and Stage 1 DBPR compliance monitoring to select Stage 2 DBPR compliance monitoring
sites. The Stage 2 DBPR provides a specific protocol for selecting these sites based on ranking the TTHM and
HAAS locational running annual average (LRAA) for each standard monitoring and Stage 1 DBPR compliance
monitoring site. This protocol is summarized in Table 3. If the system decides to recommend an alternative
Stage 2 DBPR compliance monitoring site, a justification must be included in the report.
Table 3: Protocol to Select Stage 2 DBPR Compliance Monitoring Locations
Select the location with:
1
2
3*
4
Highest TTHM LRAA
Highest HAA5 LRAA
Highest HAA5 LRAA from Stage 1 DBPR sites
(Average residence time if surface water,
maximum residence time if ground water system)
Next highest TTHM LRAA.
5
6
7*
8
Next highest TTHM LRAA
Next highest HAA5 LRAA
Highest TTHM LRAA from Stage 1 DBPR sites
(Average residence time if surface water, maximum
residence time if ground water system)
Next highest HAA5 LRAA
*skip this step if you have no more Stage 1 DBPR sites
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As with standard monitoring, you will select your peak historical month and sampling frequency. You should use
the peak historical month selected in your standard monitoring plan unless new data suggest another month.
The number of sites you select as well as the monitoring frequency is based on your source water type and
population, as listed in Table 4. If you sample more than annually, you will conduct Stage 2 DBPR compliance
sampling at equal intervals around the peak historical month, based on your required sampling frequency.
Table 4: Stage 2 DBPR Compliance Monitoring Requirements
Source
Water
Type
Population Size
Category
Monitoring
Frequency1
Distribution System Monitoring Location
Total per
monitoring
period
Highest
TTHM
Locations
Highest
HAAS
Locations
Existing Stage 1
DBPR Compliance
Locations
s
u
b
P
a
r
t
H
G
r
o
u
n
d
<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
per year
per quarter
per quarter
per quarter
per quarter
per quarter
per quarter
per quarter
per year
per year
per quarter
per quarter
per quarter
2
2
2
4
8
12
16
20
2
2
4
6
8
1
1
1
2
3
5
6
8
1
1
2
3
3
1
1
1
1
3
4
6
7
1
1
1
2
3
-
-
-
1
2
3
4
5
-
-
1
1
2
1 All systems must monitor during the month of highest DBP 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. Only one
location with a dual sample set per monitoring period in deeded if highest TTHM and HAAS concentrations occur at the same location,
and month, in monitored annually.
STEP 4: PREPARE STAGE 2 DBPR COMPLIANCE MONITORING PLAN
The required elements of the Stage 2 DBPR compliance monitoring plan are the compliance monitoring
locations, dates, and compliance calculation procedures. If you decide to include the compliance calculation
procedures in your IDSE Report, you will not have to prepare a separate Stage 2 DBPR compliance monitoring
plan. However, if you did not include the information required for the Stage 2 DBPR compliance monitoring
plan as part of your IDSE Report, your next step will be to prepare this plan before beginning Stage 2 DBPR
compliance monitoring. If you are a Subpart H system serving more than 3,300 people, you must submit a copy
of the monitoring plan to your state before Stage 2 DBPR compliance monitoring begins. Also, systems should
check with their states in case there are state requirements, in addition to the Federal requirements, that
need to be included in the IDSE Report.
ADDITIONAL GUIDANCE MATERIALS
The following guidance materials address the IDSE requirements for the Stage 2 DBPR:
• Initial Distribution System Evaluation Guidance Manual for the Final Stage 2 Disinfectants and
Disinfection Byproducts Rule (EPA 815-B-06-002) - This manual is a comprehensive technical guidance
document for all system sizes and types and all IDSE options.
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• Initial Distribution System Evaluation Guide for Systems Serving < 10,000 People For the Final Stage 2
Disinfectants and Disinfection Byproducts Rule (EPA 815-B-06-001) - This manual focuses on information
that systems serving less than 10,000 are most likely to use. It does not discuss the IDSE system specific
study option.
• IDSE Tool - Is a web-based tool that walks the user through the IDSE process. A Wizard determines IDSE
requirements and selects the best IDSE option for your system. The tool creates Custom Forms your
system (based on population served and system type) can submit electronically to EPA's Information
Processing and Management Center for EPA/state review. (Available on-line at
www.epa.gov/safewater/disinfection/tools.)
For additional guidance on the Stage 2 DBPR, you may refer to the following existing and future EPA materials:
• Stage 2 DBPR Quick Reference Guides (Schedules 1-4).
• Simultaneous Compliance Guidance Manuals for the Stage 2 Rules (draft version anticipated mid-2006).
• Stage 2 Disinfectant and Disinfection Byproducts Rule: Small Entity Compliance Guide - One of the
Simple Tools for Effective Performance (STEP) Guide Series (draft version anticipated late 2006).
• Consecutive System Guidance Manual for the Final Stage 2 Disinfectants and Disinfection Byproducts
Rule (draft version anticipated late 2006).
• Operational Evaluation Guidance Manual for the Final Stage 2 Disinfectants and Disinfection Byproducts
Rule (draft version anticipated late 2006).
Materials can be downloaded from www.epa.gov/safewater/disinfection/stage2, as they become available.
For additional information, please contact the Safe Drinking Water Hotline at 1-800-426-4791,
send an email to stage2mdbp@epa.gov. or visit www.epa.gov/safewater/disinfection/stage2.
Office of Water (4606) EPA 816-F-06-021 www.epa.gov/safewater/d1s1nfect1on/stage2 June 2006
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