This report is a retrospective assessment of dual water systems, which are two distribution systems operating jointly, one to supply potable and the other to supply non-potable water (most commonly with reclaimed water). The research tasks included an inventory of cases where dual systems have been implemented; formulation of a protocol to identify claimed benefits, costs, and risks; collection of data (quantitative and anecdotal) to assess performance; display of data in the form of performance results; and explanations of the results. Reviewing the performance of the systems presented a challenge because no standard classification system had been developed and the systems varied widely in scale, type, and stage of development. Initial groundwork towards developing a classification system is presented. Qualitative performance results are discussed in the areas of water safety and public health, effectiveness in meeting system goals, risk and reliability, total cost, and implementation and operations. The report includes short descriptions of dual water systems from 37 utilities in the United States. Research partners: WERF and EPA. Published in 2013.
Originally funded as WERF project INFR1SG09b