Household composting toilets have been around since the 1960s, but they are getting more recognition lately as Home Depot and Ace Hardware stores begin carrying the waterless toilets made by Biolet.

The general principal of a composting toilet is pretty simple: Waste and toilet paper go into a tank — either right below the toilet or pumped to a holding tank further away — where they are broken down aerobically. (That means with oxygen, and because the systems pull air through them, the claim is that they do not smell.) The breakdown is pretty complete too: Volume is reduced to about 2 percent after five years. The main advantage is that the toilets don’t use water. With some models, you can drop all your kitchen compostables into the tank, too.

In places like Sweden, composting toilets are fairly popular in homes and office buildings. In the States, they’ve more commonly been used in camps, pool houses and basements, places where it’s hard to hook up a toilet to a water system.

But with more concern about the world’s shrinking resources, interest in low-volume and waterless toilets has grown. (Not always with rave reviews; Miami Herald columnist Dave Barry has been cursing the “low-flush” toilet for years. But they’ve gotten better, Dave. Really.)

Toilets are the biggest users of water in the home — more than washing machines and showers. Per capita, Americans flush more than 18 gallons down the toilet a day, which adds up to more than 4 billion gallons of water every day. Even with a regular toilet, you can reduce water waste by displacing some of the water in the tank, so that less water is used for each flush. The recommended method is putting a sealed, half-gallon milk jug full of water in the tank. (Don’t use a brick — they crumble and can clog things up.)

Biolet says its composting toilet can be installed in a couple of hours. Costs range from about $1,400 to more than $2,100. The savings come in water use and avoiding sewer or septic hookup.

Here is a pretty good description of how a composting toilet works.

For more information on the Biolet toilet, click here. Separett, a Swedish company, also makes composting toilets, as does Envirolet, and Phoenix.

Ever considered a composting toilet? Do you know anyone who has one? Do you have tips on saving water? Share them in the comment box below, or email greenpoint@dailygazette.net.