A cartridge for placement in a urinal includes a chamber having an entry for receiving wastewater (e.g., urine), a quantity of sealant floatable on the wastewater in the chamber for functioning as a barrier to odors that may otherwise emanate from the wastewater in the chamber, a sealant reservoir coupled to the chamber for containing a supply of the sealant, and a closed path sealant dispenser for dispensing the sealant from the sealant reservoir to the chamber for maintaining the sealant modicum atop the wastewater. The sealant dispenser includes a cap having a U-shaped channel, and opening, and an orifice entering into a throat in which the sealant floats. An air vent avoids the buildup of suction in the primary reservoir. A secondary reservoir may be coupled to the sealant reservoir primarily for retaining additional sealant, in addition to any wastewater that might accompany the sealant for conserving sealant, and is particularly useful to avoid the deleterious effects of water being dumped into cartridge, particularly, sealant that is flushed out and into drain through the outlet-to-drain compartment, which flushing has a minimal effect on the sealant in the secondary reservoir. If desired, a water reservoir may be housed within the cartridge.