Total Coliform Rule and Potential Revisions and Distribution System Requirements
Introduction
EPA published the Total Coliform Rule (TCR) on June 29, 1989. The TCR
requires all public water systems (PWSs) to monitor for the presence of
coliforms in their distribution systems, as measured by "total coliforms." The
1996 amendments to the Safe Drinking Water Act [Section 1412(b) (9)] require
the Administrator to review and revise, as appropriate, each national
primary drinking water regulation not less often than every 6 years. EPA
published as part of its National Primary Drinking Water Regulation (NPDWR)
Review its decision to revise the TCR in July, 2003.
The Microbial and Disinfection Byproducts (M/DBP) Federal Advisory Committee
(FACA) agreed in principle that valid health concerns from distribution
systems exist, and that EPA should review available data and research
on distribution system risks and work further with stakeholders. These
efforts will result in the review and possible revision of the TCR, as
well as the potential for requirements to address finished water quality
in the distribution system.
EPA, in association with distribution system experts, has begun to compile
existing information regarding potential health risks that may be associated
with distribution systems in "white papers" on nine distribution
system issues. In addition, EPA is involved in the development of a series
of ten TCR issue papers. All distribution system white papers and TCR
issue papers will be used to inform EPA and stakeholders of areas of potential
TCR revisions and distribution system requirements.
Total Coliform Rule: Purpose and Requirements
The TCR requires all public water systems (PWSs) to monitor for the
presence of total coliforms in the distribution system. Total coliforms
are a group of closely related bacteria that are (with few exceptions)
not harmful to humans. Because total coliforms are common inhabitants
of ambient water and may be injured by environmental stresses (e.g., lack
of nutrients) and water treatment (e.g., chlorine disinfection) in a manner
similar to most bacterial pathogens and many viral enteric pathogens,
EPA considers them a useful indicator of these pathogens. More important,
for drinking water, total coliforms are used to determine the adequacy
of water treatment and the integrity of the distribution system. The absence
of total coliforms in the distribution system minimizes the likelihood
that fecal pathogens are present. Thus, total coliforms are used to determine
the vulnerability of a system to fecal contamination.
The TCR requires systems to monitor for total coliforms at a frequency
proportional to the number of people served. If any sample tests positive
for total coliforms, the system must perform the following additional
tests:
-
Further test that culture for the presence of either fecal coliforms
or Escherichia coli;
-
Take one set of 3-4 repeat samples at sites located within 5 or
fewer sampling sites adjacent to the location of the routine positive
sample within 24 hours; and
- Take at least 5 routine samples the next month of operation.
Stage 2 M/DBP Agreement in Principle (AIP)
As part of its recommendations concerning the Long-Term 2 Enhanced Surface
Water Treatment Rule and the Stage 2 Disinfection Byproducts Rule, the
Stage 2 Microbial/Disinfection Byproducts (M/DBP) Federal
Advisory Committee recognized the following points in its Agreement in
Principle:
-
"Finished water storage and distribution systems may have an
impact on water quality and may pose risks to public health."
-
"Cross-connections and backflow in distribution systems represent
a significant public health risk."
-
"Water quality problems can be related to infrastructure problems
and that aging of distribution systems may increase risks of infrastructure
problems."
- "Distribution systems are highly complex and that there is a
significant need for additional information and analysis on the nature
and magnitude of risk associated with them."
The FACA concluded from these points that EPA should review and evaluate
available data and research on those aspects of distribution systems that
may create or pose risks to public health as a part of the Six-Year Review
of the TCR. The FACA also concluded that, with this evaluation, EPA should
initiate a process with stakeholder participation for addressing requirements
for cross-connection control and backflow prevention, and distribution
systems issues related to significant health risks.
EPA Six-Year Review Notice of Intent (NOI)
EPA has undertaken a rulemaking process to initiate possible revisions
to the TCR. This preliminary decision was made based on the FACA agreement,
review of technical papers published since the TCR promulgation, and comments
received from a number of stakeholders. As part of the TCR rulemaking,
EPA plans to assess the effectiveness of the current TCR in reducing public
health risk, and what technically supportable alternative/additional monitoring
strategies are available that would decrease economic burden while maintaining
or improving public health protection.
EPA has completed its review of the Total Coliform Rule (TCR), 69 NPDWRs
that were established prior to 1997, including 68 chemical NPDWRs. The
intended purpose of the review is to identify current health risk assessments,
changes in technology, and/or other factors, provide a health or technological
basis to support a regulatory revision that will maintain or improve public
health protection.
EPA published its protocol for the review of the TCR, NPDWRs and preliminary
revise/not revise decisions for the 69 NPDWRs in the April 17, 2002, edition
of the Federal
Register (67 FR 19030 (USEPA, 2002g) in order to seek comment from
the public. The results of this action are contained in
Federal Register (68 FR 42907 (USEPA, 2003) which briefly describes
the major comments, other new information, and EPA's current revise/not
revise decisions for the 69 NPDWRs. In this notice EPA published its
decision to revise the TCR.
Distribution System White Papers
EPA, along with distribution system experts external to EPA, have developed
a series of "white papers". These "white papers" were
the outgrowth of two meetings of distribution system experts. The meeting
attendees included representatives from EPA's Office of Ground Water
and Drinking Water and Office of Research and Development; academia; water
utilities; Association of Metropolitan Water Agencies; American Water
Works Association; American Water Works Service Company; environmental
consulting companies; state regulators; and environmental interest groups.
The aim of the meetings was not to negotiate/generate final answers or
regulatory strategies, but to illuminate the data available on potential
health risks in distribution systems. These meetings were held in June
2000, and March 2002. The experts agreed on the preparation of "white
papers" on distribution system issues ranked of significant public
health concern (see list below). The objective of the "white papers" is
to review the available data, information and research regarding the
potential public health risks associated with the distribution system
issues, and
where relevant, identify areas in which additional research may be warranted.
The papers only present available information and do not represent Agency
policy. The topics of the "white papers" are as follows:
As part of the development of the “white papers” EPA also
developed microbial and chemical
(97K PDF FILE, 4pgs)
contaminant tables on potential health effects to support the "white
papers." The health effects tables provide a common base for discussion
of the potential health effects within each white paper resulting from
chemical and biological contaminants that have entered drinking water
distribution systems.
The white papers will serve as background material for EPA, expert
and stakeholder discussions. Some of the papers were prepared by parties
outside of EPA, therefore EPA does not endorse these papers, but is providing
them for review. These are the papers on Intrusion, Aging Infrastructure
and Corrosion, Permeation and Leaching, Nitrification, Covered Storage,
Decay in Water Quality over Time and New or Repaired Mains.
TCR Issue Papers
EPA, along with AWWA, is preparing a series of ten TCR issue papers.
The papers will present available information related to topics for potential
TCR revision. The papers are:
- Distribution System Indicators of Water Quality
- The Effectiveness of Disinfectant Residuals in the Distribution System
- Analysis of Compliance and Characterization of Violations of the Total Coliform Rule
- Evaluating HACCP Strategies for Distribution System Monitoring, Hazard Assessment and Control
- Inorganic Contaminant Accumulation in Distribution Systems
- Distribution System Inventory and Condition Assessment
- Optimization of Distribution System Monitoring Strategies
- Effect of Treatment on Nutrient Availability
- Causes of Total Coliform Positive Samples and Contamination Events in Distribution Systems
- Total Coliform Sample Invalidation
EPA will use the papers as information sources for discussions
of TCR issues with the drinking water community, experts and
stakeholders. These papers do not necessarily reflect the
views of EPA. The papers on Optimization of Distribution
System Monitoring Strategies and Distribution System Inventory
and Condition Assessment were prepared by AWWA and are being
provided by EPA for their review.
National Academy of Sciences Committee on Public Water Supply
Distribution Systems: Assessing and Reducing Risksn
The National Academy of Sciences has convened a committee to
undertake a study of water quality issues associated with public
water supply distribution systems. Information on this study can
be found at the NAS web site,
Project Title: Public Water Supply Distribution Systems: Assessing and Reducing Risks.
Stakeholder Meeting Information
No stakeholder meetings are currently scheduled. As they
are scheduled they will be posted on this web site and published in the
Federal Register.
|
