They Need to Be Maintained
Compared to flushing urinals, waterless urinals need less maintenance. Manufacturers frequently point out in their promotional materials that their urinals very rarely leak, and don't have valves or handles that need to be replaced [source: Waterless]. All of that is true, but they do need special regular maintenance to keep them working properly. The sealant liquid needs to be replaced every 1,500 uses (two to four times a year) [source: Reichardt]. Small amounts of it seep down the drain with the urine, depleting the sealant over time. Some waterless urinals also have removable trap cartridges. Depending on the brand of urinal, those cartridges need to be either removed and cleaned, or disposed of and replaced. (Many manufacturers will recycle the cartridges for you.) Sediments from urine build up over time and clog the trap cartridges. Urinals that don't have removable cartridges will need to cleaned with a plumbing snake when sediment from the urine builds up and forms obstructions [source: Stumpf].