ARLINGTON, VA, June 5, 2014 — According to recent statistics, a number of cities throughout the globe are experiencing increased water stress and looking for additional water supplies to support their continued growth, as more people move to urban areas.
The first global database of urban water sources and stress, published in Global Environmental Change on Tuesday, June 3, estimates that cities move 504 billion liters of water — enough to fill 200,000 Olympic swimming pools — a distance of 27,000 kilometers every day. While large cities only occupy 1 percent of the Earth’s land surface, theirsource watersheds cover 41 percent of that surface, so the raw water quality of large cities depends on the land-use in this much larger area.
Four in five (78 percent) urbanites in large cities, some 1.21 billion people, primarily depend on surface water sources. The remainder depend on groundwater (20 percent) or, rarely, desalination (2 percent).
The urban water infrastructure of large cities cumulatively supplies 668 billion liters daily. Of this, 504 billion liters daily comes from surface sources, and that water is conveyed over a total distance of 27,000 km.