Distribution System Indicators of Drinking Water Quality
As part of the revision of the Total Coliform Rule, USEPA published a series of issue papers to present available information on topics relevant to possible TCR revisions. The objectives of the issue papers were 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 issue papers serve as background material for EPA, expert and stakeholder discussions. The papers only present available information and do not represent Agency policy. Some of the papers were prepared by parties outside of EPA; EPA does not endorse those papers, but is providing them for information and review.
Distribution System Indicators of Water Quality
This paper identifies and characterizes potential indicators of distribution system contamination, particularly those related to unexpected contamination of the distribution system. Microbial indicators discussed include total coliforms, fecal coliforms, E. coli, enterococci, fecal streptococci, somatic coliphage, f-specific coliphage and heterotrophic bacteria. Various chemical (e.g., sterols, turbidity, AOC) and physical indicators (e.g., water loss, pressure drops) are examined. Data indicating a potential relationship between public health risk and the indicators are discussed.