Waterless Urinals - Saves $$$, but will they last?

Recently I've been seeing more and more waterless urinals. There's always a sign above them touting the benefits, how they save thousands of gallons of water per urinal every year. But there are a few problems. One big one in fact: they usually smell terrible.



I researched how these things work. If you're basically familiar with plumbing, you'll know that most all sinks, toilets, etc. have a U shaped trap at the drain (look under your sink and you'll see). Here's the reason. Without a trap, all of the waste water would flow straight out of your house to the sewage system immediately. Then bad odors from the sewer would start seeping back into the house through the same lines. Gross... So to combat this, there is that U shaped trap that keeps a little bit of water stuck in there to prevent any air/odors from coming back in.

Urinals have the same thing. Generally when you flush, water washes the waste down, and fresh water stays in the trap (and in the bowl). With waterless urinals, nothing stays in the bowl. It all goes down. In addition, janitors will pour a thick liquid in the urinal. It gets stuck in the trap, but rises to the top (think about how oil mixes with water). It can generally stay in the urinal for weeks, and keeps the odors out. Every couple of weeks, the janitor will flush out the urinal with some water to clean it, then add the thick liquid again to "re-seal" it.

But whatever this liquid is doesn't work very well. Smells continue regardless. I have noticed that some places have now shifted back to conventional urinals.

Although the concept makes sense, it may not be totally ready yet for the full release.