a waterless urinal meeting u . s . sanitation code requirements and providing advantages of cost savings , water conservation and easy maintenance is particularly beneficial in public or institutional urinal facilities . an odor trap cartridge unit is configured as a coaxial dual chamber bell trap that eliminates the need for conventional p or j type traps required in water - flushed urinals . in the odor trap , a body of oily liquid sealant , floating on a body of trapped residual urine , serves as an odor barrier but allows entering urine to immediately permeate downwardly through the sealant and proceed to a drain without requiring flushing . the odor trap is molded from two plastic parts that are assembled together to form a cartridge unit that fits readily into a receptacle cavity of urinal bowl configured for wall mounting . the cartridge stays in place by friction and gravity , and can be easily removed with a special tool . a special low specific gravity sealant formulation , ensuring efficient operation , is made biodegradable to protect the environment against any traces escaping to the drain . sealant replenishment , when required , is easily performed . for unusually frequent usage , maintenance may be reduced by the use of an auxiliary oil reservoir serving one or more urinals .