Augmentation of Reclaimed Water with Excess Urban Stormwater for Direct Potable Use

Groundwater and surface water have been the primary sources of our public water supply around the world. However, rapid population and economic growth, as well as global climate change, are posing major threats to the quality and quantity of these water resources. Treated wastewater (reclaimed water) and stormwater are becoming more important water resources. Use/reuse of these unconventional water resources can enable a truly sustainable, closed-loop, circular water system. However, these two sources are not usually mixed with each other. In this study, we propose the use of combined excess urban stormwater and reclaimed water as a source of potable water supply. One of the most pronounced benefits of this proposed scheme is the possible elimination of costly and energy-intensive processes like reverse osmosis. Reclaimed water tends to have high concentrations of dissolved solids (>500 mg/L) and nitrate-N (>10 mg/L), which can be lowered by blending with stormwater or rainwater. Despite technical and engineering challenges, this approach can benefit various communities—small, medium, large, upstream, downstream, urban, and rural—in diverse climates. Our study suggests that this new holistic approach is feasible, enabling the combined water to be directly used as a sustainable drinking water source.