Estimation of Chloramine Decay in Drinking Water Distribution Systems

Development of a means to identify and predict factors associated with chloramine decay in drinking water distribution systems could assist in providing targeted operational strategies which ensure regulatory compliance and ultimately lead to major cost-savings. In this study, novel bench-scale pipe section reactors (PSRs) were utilized to evaluate the impact of source water (surface or groundwater), pipe material, pipe age, and flow velocity on chloramine decay in a distribution system in the Greater Toronto Area, Ontario, Canada. Batch tests in amber glass bottles quantified decay in treated water which were compared to low- and high-flow PSR experiments to elucidate the impact of water velocity and pipe material on monochloramine decay. Of the factors examined, pipe material and condition (e.g., old or new) were identified as the most critical. Overall, the results of this study reinforce the importance of determining the source of residual disinfectant decay when considering chloramination.M.A.S