OFFICE OF GROUND WATER
AND DRINKING WATER
In-Depth Analysis
Stage 2 DBPR
oEPA
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WHAT IS A SDWA IN-DEPTH
ANALYSIS (AKA DEEP DIVE)?
The goal of an in-depth analysis is to identify
compliance challenges related to a specific regulatory
requirement and to share best practices for enhancing
implementation. This national effort is strategic in
scope, is conducted as a joint effort between EPA and
the states, and supports EPA's breakthrough measure
to reduce the number of community water systems
(CWSs) with health-based violations by 25% within
five years.
EPA works with the states to select areas for analysis
and seeks state volunteers to participate in the effort.
EPA and the states work together to:
•	Understand the root cause of the implementation
issue;
•	Seek state best practices; and
•	Develop and provide targeted training
and technical assistance to enhance the
effectiveness of the SDWA program.
STAGE 2 DBPR AND CONSECUTIVE
SYSTEM CHALLENGE
The National Primary Drinking Water Regulation
(NPDWR) with the largest number of CWSs in violation,
roughly 30% of all violations during fiscal year 2017
(FY17) and 2018, was the Stage 2 Disinfectants and
Disinfection Byproduct Rule (DBPR). As shown in
the figure, more than half of the systems in violation
were consecutive CWSs, with a violation rate of
4.9% for consecutive CWSs compared to 1.4% for
non-consecutive.
As part of this in-depth analysis, EPA worked with five
state partners, Indiana, Kentucky, New Jersey, North
Dakota, and Pennsylvania, to evaluate this compliance
challenge and share lessons learned and best practices.
Consecutive
13,457
Total
Non-Consecutive
968
7.2%
663
4.9%
50,259
Systems
in Violation
3,508
Violation Rate
7.0%
overall
Systems
with Stage S
DBPR violations
1,188
Violation Rate
2.4%
Stage 2 DBPR
36,802
525
6.9%
2,540
1.4%
Rates of Stage 2 DBPR health-based violations at
consecutive CWSs and non-consecutive CWSs (FY17).

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NATIONAL DATA ANALYSIS
The first step in this in-depth analysis
was to conduct a national data analysis
to identifyareasofthe United States with
Stage 2 DBPR compliance challenges
and evaluate common characteristics
of the CWSs that were out of compliance. General findings
based on FY2017 data included the following:
•	Location of Stage 2 DBPR health-based
violations: Systems in violation generally
formed a band from the mid-Atlantic states down
through Texas, along with Alaska and Puerto
Rico; consecutive systems showed a similar
geographical pattern, though the percentage of
systems in violation was greater.
•	Maximum Contaminant Level (MCL)
violation type: CWSs can have a violation of
the total trihalomethanes (TTHM) MCL, the five
haloacetic acids (HAA5) MCL, or both MCLs. TTHM
MCL violations (systems with a TTHM or both
TTHM and HAA5) were dominant comprising
approximately 80% of the systems in violations.
This pattern is slightly more pronounced at
consecutive CWSs (83%) than in non-
consecutive CWSs (76%). In contrast, systems
with HAA5 MCL violations were higher at non-
consecutive CWSs (43%) than at consecutive
CWSs (33%).
•	Source water: Stage 2 DBPR violations are
a greater issue for surface water systems,
especially for purchased water systems. Violations
for non-consecutive systems were approximately
62% surface water, whereas 37% of violations
were for ground water sources. This relationship
is even more pronounced for consecutive systems
where approximately 81% had a surface water
primary source, compared to approximately 18%
for ground water.
•	System size: TTHM and HAA5 MCL violations
occurred most frequently, and at higher
concentrations above the MCL, for those
systems serving approximately 1,000 persons;
the pattern is similar for both consecutive and
non-consecutive systems.
STATE BEST PRACTICES
s*
Information on state best practices
was based on site visits to the five
partner states, as well as feedback
from 32 other states provided by Association of State
Drinking Water Administrators (ASDWA). General
lessons learned include:
•	Alabama and Tennessee require sample
collection at the system's interconnection with
the consecutive system and the wholesalers
must conduct an operational evaluation level
(OEL) report when they are triggered by the
consecutive system.
•	Several states use system optimization and
training programs to evaluate treatment
plant processes and distribution system issues.
Such approaches allow systems to identify the
root cause of the disinfectant byproduct (DBP)
challenge and develop approaches to improve
system performance.
•	Kentucky's drinking water program works
in coordination with their enforcement program
to identify the root cause of the systems'
DBP violation and develop a path to return to
compliance, often using a system optimization
approach.
•	Several states mentioned challenges with
different laboratories producing variable results
that are above and/or below the MCL. Best
practices suggested from EPA's Technical
Support Center (TSC) include using newer
laboratory methods (552.3, 524.3, and 524.4)
that utilize newer instrumentation, as well as
additional quality control specifications.
•	North Dakota provides peer training sessions
at their annual state conference by bringing in a
panel of operators who have dealt with common
challenges and sharing their approaches to
returning to compliance.
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For more information, visit: https: //www.
epa.gov/dwreginfo/diving-regulations
OFFICE OF WATER
EPA 815-F-19-001
April 2019

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