A Qualitative Definition of Reliable Water Supply for Public Water Systems

Abstract

“Reliable water supply” does not have a clear definition in the Western United States, where water resources are limited and such a definition would be especially useful. In Utah, the three water agencies and 500 public water systems have no consistent method to define, evaluate, and report it, potentially leading to an inability to meet regulatory water demands. We propose a unified definition of reliable water supply for Utah’s public water suppliers that can also be used elsewhere. We derive our definition from a two-part qualitative analysis: (1) an extensive review of existing definitions in industry and academia and (2) semi-structured interviews with managers of six diverse Utah water utilities. We propose that water supply be defined by three overlapping components—hydrology, infrastructure, and governance—and that reliability be defined by the capacity of the limiting component. The results from the qualitative analysis support our definition and further indicate that a definition is necessary to precede quantitative evaluations, set policy, and provide consistency to water resources management.