A vacuum toilet system for a vehicle (such as a boat) has numerous advantages. A single pump with valves on opposite sides of it may be used as both the vacuum source and for discharging sewage from a holding tank. Two sets of multiple heads may be selectively connected to two pumps for emergency purposes. The vacuum toilet includes a sealing element with an integral movable valve engaging element including polytetrylflouroethylene and synthetic rubber, and at the same durometer (55-65). The initial passageway provided by movement of the valve with respect to the seal is disposed directly above the center line of an orifice. An an anti-siphon valve assembly has a simple construction of a housing with parallel legs and anti-siphon air passage in alignment with one of the legs. A spray nozzle extends from the other legs of the anti-siphon valve assembly. The toilet funnel/orifice is universally connected to conduits. The vacuum tank is blow molded of plastic, has universal ports including one continuous from the tank walls so that no accumulation takes place in the tank. Longitudinal ribs along the tank provide for easy connection to a support. A vacuum sensor is mounted to one of the vacuum tank ports with fasteners disposed exteriorly of the tank, and without the need for an O-ring.