Flushless Urinals: How Do They Work?

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Gentlemen, have you ever been standing there reading that placard that proudly announces you’re using a flushless urinal and wondered, “If it doesn’t flush, how does it work?” Water-free urinals are showing up in more and more places thanks to the years long drought in the Southwest, and they’re even making appearances in regions where water conservation isn't as pressing of an issue.

So the question is - if they’re not flushing, what are they doing?

The Technology

Different manufacturers have different features, but they all boil down to the same thing. Your contribution to the system drains via gravity into a trap (a P-trap?), but unlike in a normal urinal this trap is pre-loaded with water and a proprietary, oil based liquid that floats on top of it. The urine passes through the oil cap, which prevents odors from escaping back out of the drain. Periodically, the oil fluid has to be replaced, sometimes directly into the drain, and sometimes in the form of a removable cartridge that also contains filters and deodorizers.

The added technology is all there to prevent odors. Without it you could still use your flushless urinal, it would just smell like the ones at the beach.