Waterless urinals are a technology closely related to composting toilets. Both are designed to provide a sanitation solution without the use of clean, valuable water.
Waterless urinals general have a “trap,” that acts like an S-Trap found on a conventional toilet, designed to prevent odour. These traps generally use a plastic insert or cartridge with some sort of chemical in it. (More research is required as to what the chemical is…)
“Conventional urinals use at least three liters of water per flush (about a gallon), whereas flushless urinals need neither water nor a flushing system […] Special glazes give sanitary-ware urinals a pore-free surface, while urinals made of synthetic material have a long-lasting gel coating that repels liquids. The urine flows off the smooth surface of the urinal into a siphon. […] The siphon contains a liquid sealant that has a specific density that is lighter-than-water. This floats to the top, allowing the urine to flow through it and away, taking any odors with it. The liquid sealant remains in the siphon. Flushless urinals have no joints or cracks in which bacteria can colonize. The special surface repels most liquids and impurities. Cleaning therefore involves less cost and effort than with conventional systems, and strong toilet cleaners are unnecessary.”
Another positive, is that waterless urinals do save a lot of money vs. a standard urinal. According to the Triple Pundit case study, replacing 14 urinals with flushless waterless urinals would amount to a $800 savings.
Are they problem free? Some of the comments on Treehugger would seem to say no. There are complaints of “splash-back” and odour. Both of these problems could probably be explained as being the result of a clogged (or blocked from someone things that shouldn’t be in the urinal like cigarette butts) “trap.” The traps do need to be replaced occasionally and if they are full, they can leave urine in the urinal, causing odour.
To compare, composting toilets prevent odour using negative pressure (via the vent system and a constant draw of air through the toilet bowl area).
Overall, I think the idea of waterless urinals is great. Just imagine the amount of water saved worldwide if waterless urinals were in place in public buildings.
Waterless urinals are definately something that Composting Toilet World will investigate further.