TALLAHASSEE, Fla. — In a country like the United States, one of the human body's most urgent needs is taken for granted. It comes easily out of our faucets, and gallon jugs of it cost less than a dollar.

Until something like a hurricane makes clean drinking water hard to find.

But the Southeast's climate provides something besides hurricanes in summer: Humidity.

As emergency officials ponder how to better help their residents after disasters, some companies are pushing machines that pull the humidity from the air and turn it into drinking water. A few are also touting the machines as a potential solution to the clean-water shortages that plague the Third World, pushing aside concerns that the machines are inefficient and require fuel that also might be scarce.

The biggest machines can make 5,000 liters of water a day, enough to provide about a gallon each to 1,250 people. Small units cost several hundred dollars, while the biggest, most elaborate cost half a million.

"Tap-water systems get knocked out, bottled water often disappears even before the storm shows up ... so this becomes a way to get drinking water that you can count on no matter what," said Jonathan Wright, president of Ogden, Utah-based AquaMagic. The company recently towed a portable unit around the southeastern U.S., visiting fire departments, rescue workers and city officials to drum up interest.

AquaMagic's unit is too small to provide water for a whole city, but could at least provide water for rescue and cleanup workers so they wouldn't have to cart in truckloads of it, Wright said.

One potential buyer is David Roberts, who as fire chief in Biloxi, Miss., oversaw crews working in the aftermath of Hurricane Katrina, which leveled much of his city. "You don't realize how bad you need water until you don't have it," Roberts said. "In August, the humidity's 95 percent and it's 95 degrees. You can drink a quart of water and it goes right out of you in about 30 minutes."

He called the AquaMagic machine "a great piece of equipment. The water tasted good, too."

Most companies making the machines aren't focused on the U.S. market. Some, including one based in Miami Beach and another in Hollywood, Fla., are selling where clean drinking water is always hard to find — villages in the developing world.

"Right now at any given time, there's about 1.2 billion people that are drinking contaminated water," said Ron Colletta, vice president of sales for Island Sky Corp. in Hollywood.

Scientists who study water shortages say there are cheaper and easier ways to provide large-scale water purification if cleanliness is the issue.

The simplest is boiling it to remove microbes, or treating it with chemicals like chlorine, said 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 has a problem in some poor areas.

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

The biggest obstacle to wider use is making the machines cost-effective in fuel. Most are powered by diesel fuel. Some run on solar energy, but the panels require a costly initial investment.

Michael Zwebner, president of Miami Beach-based Air Water Corp., admits power is a big problem, but says the machines can be useful where there isn't enough water to begin with — or where people can't afford to pump it from the ground and treat it.

"In many parts of Africa, there is no water," Zwebner said.

Air Water's machine was used after the 2004 Asian tsunami, and the military in India has recently signed on to send it into the field with troops.

"In some countries in Africa they actually see this machine as an act of God," Zwebner said.