Biologically stable water is produced when all nutrients that might support significant bacterial growth in finished water have been sufficiently removed. While definitions of biostability in drinking water exist, they are primarily based upon European practice, where distribution systems are operated in the absence of a residual disinfectant. This Webcast presented the results from
, which is the first North American study to quantify the definition of biostability on a distribution system-scale in the presence of a disinfectant residual. In addition to the research report, a guidance manual and biostability assessment tool (BSAT) were developed. The tool will help utilities (1) track historical data, (2) benchmark data against results from this project, (3) assess system stability over time, and (4) identify controlling factors influencing biological stability on a site-specific basis.