Incinerating toilets can also be waterless. Instead of breaking down waste biologically, these toilets torch it. They send the waste to an incinerator, where it's burned to sterile ash.
The toilet sits in your bathroom and has an electric exhaust pipe that exits through your roof. To run, it needs batteries or can be plugged into a wall outlet. You use the toilet normally, toilet paper and all. But before you flush, you must close the lid, for reasons that will soon be clear. Next, you decide whether to press the "urine" or "[solid] waste" button on the control panel.
Then the toilet fires up. Flushing is handled by some type of dry method, like an auger (essentially a large screw) that turns to push the waste into the incinerator. A propane, diesel or natural gas tank feeds into the incinerator. The incinerator injects fuel and ignites your waste, burning it -- in one example, at 800 F (427 C). Urine cooks for up to 10 minutes; solid waste takes about half an hour [source: Ecojohn].
Like composting toilets, these toilets can be self-contained or remote, putting the incinerator either inside or outside of the toilet. Self-contained models have you practically sitting on the incinerator, which sounds alarming, but the system will shut off if you open the lid to use it.
These systems thoroughly insulate you from your excrement. Waste is almost immediately changed into something else. You don't need to inspect the waste, tend to it during its transformation or guess about its progress. It's time to empty the toilet when the indicator light tells you so. In a house of four people, Ecojohn estimates that you'll empty the ashes every three to six months [source: Ecojohn]. And you can throw the sterile ashes in the trash.
An Ecojohn setup costs about $4,000 [source: Propane]. Beyond that, you also pay for propane. Ecojohn says fuel for its toilets costs eight to 10 cents per flush [source: Ecojohn]. Bear in mind, though -- while you conserve water, unless you buy and add a catalytic converter, your incinerator puffs out fossil-fuel fumes [source: Ecojohn].
Read on for some things to consider before installing a waterless toilet.