A lot depends on whether California's drought continues. Desalting facilities are the norm in places that lack other water sources, such as the Middle East and Australia. The few plants that exist in the U.S. were originally built during or right after dry spells, but were later mothballed when the need for water proved less imminent. Today, however, with water becoming more and more precious, some of those plants may come back to life.

In 1992, a $250 million plant in Yuma, Ariz., that treats brackish groundwater was shut down due to flood damage almost as soon as construction was completed. Last year, the U.S. Bureau of Reclamation tested the 100-million-gallon-a-day plant at 10 percent of capacity for three months. Authorities have found $15 million worth of cracks in the welds of many pipes. Nevertheless, they hope to restart the Yuma plant at about one-third of capacity next year. Poseidon has another desal plant up its sleeve, as well: a proposed plant up the coast in Huntington Beach for which the company expects to get final state approvals by next summer. Environmentalists will fight it, too, as will many Huntington Beach residents, although the city council supports it.

In El Paso, Texas, water officials opened a 27-million-gallon-a-day groundwater plant last year. It's only running at a fraction of capacity right now, but at full tilt it should end the area's long history of water shortages, and guarantee enough for a huge expansion at neighboring Fort Bliss Army Base. According to Tom Pankratz, the desalination consultant, two recently built brackish-water plants are running smoothly in central California, several new seawater plants are in the works in Florida, two plants are under construction in Massachusetts, and a wind-powered facility is under study in Texas.

Yet Pankratz agrees with other experts that all desalination plants must be handled with extreme care and constructed at deliberate speed because of their cost and complexity. 

A variety of researchers have joined California officials and the Coastal Commission in endorsing desalination, at least in theory. Both the National Academy of Sciences and the Pacific Institute, an environmental think tank, say they believe it will be part of the West's water future. But they also agree that a long list of uncertainties about cost, energy and environment must be resolved.

"In the end, decisions about desalination developments will revolve around complex evaluations of local circumstances and needs, economics, financing, environmental and social impacts, and available alternatives," says the Pacific Institute in a 2006 report.

Conner Everts says that desalination is tantamount to a religion in San Diego. That may be so, but with plenty of heretics worried about fish, energy use and expensive water, it might pay to take desalination with a grain of salt. 

This article was made possible with support from the William C. Kenney Watershed Protection Foundation and the Jay Kenney Foundation.