
There's no water which is what a waterless toilet shouldn't have. In the drain sits a cartridge with a lighter-than-water sealant that keeps the oder in the pipes. The cartridge needs to be changed periodically and, yes, the urinal itself needs to be cleaned daily, but it's estimated that a waterless toilet can conserve between 15,000 and 45,000 gallons of water per year! That's as many as 670 bathtubs full of water!
To talk to people who've thought about installing them, though, you get a different picture. It seems that the cartridges and sealant are not cheap. Also, if they're not changed soon enough, sealant can leak and the odors are released--not pleasant. The sealant is supposed to be bio-degradable, but who knows? The plastic cartridge is supposed to be recyclable but where do you put it? It's not like you can chuck it into the soda bottle bin.
Time will tell if the U.S. opens its arms to the waterless urinals!