In addition to catching raindrops, homeowners and building managers are trying out another way to conserve water: composting toilets.

Last month the city of Austin, Tex., approved its first composting toilet. Columbus, Ohio is adding some composting toilets to its parks. Officials in Dutchess County, N.Y., are studying the concept.

The toilets are supposed to use no water and, over time, create a usable fertilizer. Many are supposed to be used indoors (although the Austin model, which appears to be different, is for an outhouse-type unit).

People put composting toilets in all kinds of places, according to Jim Weaver, the operations manager of BioLet, a composting toilet maker. “Boathouses. Pool houses. Barns. Workshops. Cabins. Anywhere where it’s not convenient or economical to put a conventional toilet,” he said.

Mr. Weaver said that business grew about 80 percent last year, but the recession caused a sharp drop. Things have picked back up in the past several weeks, however. Mr. Weaver said that the company typically sells more than 1,000 units a year.

BioLet’s fastest-growing markets include Florida, Virginia, Arizona and Nevada. Also, “Alaska is just booming,” he said, crediting an improved distribution system coupled with a “lack of ability to put in septic systems and such because of the permafrost.”

The company’s largest markets are Maine and the upper Midwest (where they are popular for cottages), as well as the Northwest, Texas and Colorado.

If you want to put in a composting toilet, the first thing to do is check with your local health department, said Tom Bruursema, general manager of the wastewater treatment unit program at the National Sanitation Foundation International, which sets standards for composting toilets and handles certification for some brands, such as Sun-Mar and Clivus Multrum.

“Anytime you’re dealing with residential wastewater, you have to have a permit from the health department,” he said. “That’s as true for a septic tank as it is for a compost toilet.”

A few people have reported some difficulty with their composting toilets. The units are not supposed to smell, but this blogger reported getting a whiff anyway.

Then, of course, there is the gross-out effect. Mr. Weaver said that BioLet’s toilets have to be emptied out about once every two months, depending on usage. This entertaining piece in The Los Angeles Times recounts how the author bought a composting toilet, used it a few times, then let it idle for two months — until she got the courage to empty it, which she now does on a regular basis.