Save Water, Make Money These drought-busting businesses have discovered the fountain of wealth.

Shrinking mountain snowcaps. Dwindling aquifers. Lakes reduced to ponds, ringed by enormous parched shores. Cities enforcing drastic water-use restrictions.

Parts of the U.S. are already experiencing these problems, and researchers who study climate change and water consumption patterns around the world say it will only get worse. Already one-sixth of the world's population lacks access to clean water. In the U.S., parts of the West and Southwest are experiencing what Gale Norton, former Secretary of the Interior, has called "perhaps the worst drought in 500 years."

Amid growing anxieties about water scarcity, hundreds of entrepreneurs are responding with products and services designed to help conserve this precious resource. Partners Jon Grobe, 36, David Morgan, 40, and Ken Scheer, 33, of Calsaway Pool Services Inc. in Tempe, Arizona, are targeting one of the Southwest's biggest water wasters: swimming pools. People in the Phoenix area have to drain their pools every two to four years because a buildup of minerals in the water blocks the effectiveness of pool disinfectants and damages pumps. Grobe and Morgan devised a patent-pending mobile filtration unit that strips minerals and other problematic substances from pool water. As a result, pool owners can use the same water for up to 12 years. "Last year, Calsaway saved the Phoenix area nearly 7 million gallons of water," says Scheer, who expects 2008 sales to reach $350,000.