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 proposed as part of its National Primary Drinking Water Regulation (NPDWR) Review to revise the TCR.
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. These papers are intended to inform stakeholders and provide a basis of understanding for future stakeholder meetings on the issues.
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:
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Further test that culture for the presence of either fecal coliforms or Escherichia coli;
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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:
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"Finished water storage and distribution systems may have an impact on water quality and may pose risks to public health."
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"Cross-connections and backflow in distribution systems represent a significant public health risk."
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"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 intends to undertake 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 received public comments on the NOI through June 17, 2002 and will review these comments, along with any new peer-reviewed data to make a final revise/not revise decision. A decision to revise starts a regulatory process involving more detailed analyses concerning health effects, costs, benefits, occurrence, and other issues relevant to 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.
June 2000 – The goal of this meeting was to discuss distribution system issues that have the potential to impact the public health risk. The experts agreed on the preparation of eight "white papers" on distribution system issues ranked of significant public health concern. Shortly after the meeting, the experts agreed to add a ninth "white paper" (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 topics of the "white papers" are as follows:
March 2002 – Distribution system experts reviewed the nine "white papers," gave input on the appropriateness and completeness of information, and suggested revisions. An agreement was reached to develop microbial and chemical 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 in a series of meetings with stakeholders.
Stakeholder Meeting Information
EPA will present the available information and participate in an open dialogue to identify high-priority issues to be addressed through regulatory development. Public meetings will be held across the country to solicit information:
The "white papers", tables that summarize health effects information, and short fact sheets based on each distribution system white paper will be available at each stakeholder meeting. Each meeting will also include discussion of the Total Coliform Rule.
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