Abstract: A valve and vent assembly for a self-contained sanitary system of the type including a toilet structure with a downwardly directed outlet opening and a storage compartment defined and located below the outlet opening, and a waste holding tank removably disposed within the storage compartment. The tank has a fill opening positioned in registry with the outlet opening when the tank is inserted within the storage compartment. The valve and vent assembly is operable to close the fill opening and to seal the tank to prevent leakage of waste from the tank through the fill opening, a vent passage in the storage compartment and communicating with the waste holding tank extends outside of said compartment thereby enabling noxious and odorous air in the holding tank to pass out of the tank.