Harnessing urban water demand: Lessons from North America

Urbanization stresses water resources by disrupting the natural flow of Earth’s freshwater systems, concentrating demand and separating modern industrial societies from the natural lakes and rivers that provide water to homes and businesses. Globally, water for urban or domestic uses averages only 10 percent of all withdrawals from nature (agriculture is by far the largest sector for consumptive water use), but is exceedingly important for human welfare (World Water Assessment Programme, 2009). McDonald et al. (2011) estimate that 150 million people now live in cities with persistent water shortage; this number is projected to rise to as much as one billion in 2050. More effective management of urban water demand is vital for climate adaptation, sustainable development, environmental protection and global food security.