Wright said the concept of pulling water from the air is not new, but there is a "this-can't-be-real reaction from people" every time he catches the water into the cup.

The tour started in June in Houston — with the slogan "Houston We Have A Solution" — and fed off the city's aid to Hurricane Katrina and Rita victims. The tour ended in Washington, where the pair met with World Bank officials and chapters of the Red Cross. Wright and Richards hope local officials will purchase the machines as a safety tool but also want to market around the world.

They initially visited South Africa to gauge the need and interest for this type of machine. Wright said about 1 million people there live in shack-like houses that have electricity but no clean water. He said the machines could help bring that water to them.

Scientists who study water shortages say that while the technology works simply and could be part of the solution, there are cheaper and easier ways to provide large-scale water purification if cleanliness is the main issue.

The simplest method is boiling water to remove microbes, or treating it with chemicals like chlorine, said Dr. Mark Sobsey, a professor of environmental sciences and engineering at the University of North Carolina School of Public Health's Drinking Water Research Center.

But boiling is a problem in some poor areas.

"You've got to have fuel and to be able to pay for it," Sobsey noted.

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Contributing: Associated Press.

E-mail: suzanne@desnews.com