Operating Water Distribution Systems for Equitable Access to Clean Water

Urban water distribution systems (WDSs) are designed to deliver potable water to all end users. Unpredicted changes in water demands and hydraulics can increase residence time in pipes (water age), leading to growth of microbes and decreased water quality at some locations in a network. In response to reduced water quality, consumers may reduce demands for drinking, cooking, and cleaning. Lack of access to clean water can create high costs for some households due to the cost of using bottled water, paper plates, and laundromats for daily activities. This research develops an optimization framework to design operational strategies that maximize equity in a community that uses a WDS. Reduced demands and inequitable access to clean water are explored in this research in the context of the COVID-19 pandemic through a coupled framework. First, an agent-based modeling (ABM) framework is applied to simulate COVID-19 transmission, social distancing decision-making, and reductions in water demands. Large-scale reductions in demands, especially in industrial and commercial areas as individuals worked from home, leads to hot-spots of increased water age. The ABM is extended in this work to simulate households that choose to reduce demand from the system by buying bottled water for cooking, cleaning, and hygienic purposes. Equity is evaluated using an adjusted income metric that includes the cost of water bills and supplemental bottled water. A graph theory approach is applied to open and close valves to maximize equity. The coupled framework is applied for a virtual water distribution system, and results demonstrate operational strategies that improve equity for a community. This research develops an equity metric that assesses the water quality of delivered water and can be used to facilitate WDS management that provides equitable access to clean water.