Drinkable Sea Water

With its wet surroundings, Key West, Fla., the southernmost city in the continental U.S., is ideal for conch shell collecting and deep-sea fishing, but it has been hard up for fresh water. The city long had to rely on a 130-mi. Navy-owned pipeline to the mainland, a source vulnerable to hurricanes, drought and, recently, the Navy's rising water appetite at its own local bases.

Last week, Key West became the first U.S. city to get its entire freshwater supply from the sea when the Florida Keys Aqueduct Commission dedicated the world's largest single-unit desalting plant, a gleaming $3.3 million facility that can produce up to 2,620,000 gallons a day. The plant uses the so-called "flash" process, by which heated sea water is forced through a series of low-pressure chambers until it vaporizes into steam, which, in turn, condenses into pure water--much as steam condenses on the surface of a tea kettle. Fifteen years ago, desalination cost up to $5 per 1,000 gallons; with the flash method, it now costs 850.

Desalting facilities are in operation in places like Kuwait, Curac,ao and Israel. In the U.S., with technical assistance from the Interior Department's Office of Saline Water, Buckeye, Ariz., and Port Mansfield, Texas, both turned to desalination after their water became too brackish. With the threat of water shortages and pollution mounting, other cities can be expected to follow suit, especially as nuclear power becomes available to make large-scale desalination projects more economical.

By 1973, parts of Los Angeles will start getting converted sea water from a nuclear-powered 150 million-gallon-a-day plant. The U.S. and Mexico may put up a billion-gallon-a-day plant on the Gulf of California in the 1980s. By that time, the cost of desalting water could be cut to 100 per 1,000 gallons. Speaking over the noisy hum of Key West's desalting plant last week, Vice President Hubert Humphrey ventured a bold prediction. With such breakthroughs, he said, desalination will eventually yield benefits "as great as those bestowed by the development of electricity."

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