National Geographic : 2010 Apr
ART BY BRYAN CHRISTIE SOURCES: TOM PANKRATZ, GLOBAL WATER INTELLIGENCE; INTERNATIONAL DESALINATION ASSOCIATION; MARK A. SHAN NON, UNIVERSITY OF ILLINOIS; ALEKSANDR NOY, UNIVERSITY OF CALIFORNIA, MERCED THREE HUNDRED MILLION PEOPLE now get their water from the sea or from brackish groundwater that is too salty to drink. That's double the number a decade ago. Desalination took off in the 1970s in the Middle East and has since spread to 150 countries. Within the next six years new desalination plants may add as much as 13 billion gallons a day to the global water supply, the equivalent of another Colorado River. The reason for the boom is simple: As populations grow and agriculture and industry expand, fresh water---especially clean fresh water---is getting scarcer. "The thing about water is, you gotta have it," says Tom Pankratz, editor of the Water Desalination Report, a trade publication. "Desalination is not a cheap way to get water, but sometimes it's the only way there is. " And it's much cheaper than it was two decades ago. The first desalination method---and still the most common, especially in oil-rich countries along the Persian Gulf---was brute-force distillation: Heat seawater until it turns to steam, leaving its salt behind, then condense it. The current state of the art, used, for example, at plants that opened recently in Tampa Bay, Florida, (Continued on next page) Get the Salt Out There's no shortage of water on the blue planet--- just a shortage of fresh water. New tech- nologies may offer better ways to...