As urban populations rise, cities will need to rethink they way they provide freshwater for their citizens, and how they process dirty water.
"[T]his next urban evolution cannot occur without crisis unless we reinvent our current paradigm of urban water supply and management to meet the demands of the dawning age of freshwater scarcity. In more and more parts of the world, demand is outstripping available supply of freshwater and water ecosystems are being tapped beyond sustainable replenishment rates. As a result, urban domestic needs are competing for limited supplies against other vital, water-intensive activities such as producing food, energy, and industrial goods. States that cannot feed, power, or provide adequate domestic water to their societies are highly prone to weaken and fail. Just as oil shortages transformed the history of the 20th century, freshwater scarcity is emerging as one of the defining fulcrums of geopolitics, national security, economics, environment, and daily living conditions of the 21st century."