Peak water is here and unlike peak oil, there is no substitution for water. But like peak oil the low-hanging fruit of our fresh water supply has been picked and what is left requires costly environmental and financial impacts to extract. Peak water is about reaching physical, economic, and environmental limits on meeting human demands for water and the subsequent decline of water availability and use. There is a vast amount of water on the planet but sustainably managed water is becoming scarce.

Today some 18 countries, containing half the world’s people, are overpumping their aquifers. Among these are the big three grain producers—China, India, and the United States—and several other populous countries, including Iran, Pakistan and Mexico.

Dr. Peter Gleick is a world-class expert in climate and hydrology, a winner…