Abstract: A vacuum breaker for use in a fluid supply system is provided. The vacuum breaker comprises a body having an interior, a fluid inlet, a fluid outlet, and an atmospheric air vent. The body is adapted to permit fluid to flow through the interior from the fluid inlet to the fluid outlet. A first seat disposed within the interior of the body. A bonnet having a second seat communicates with the air vent and the interior. A displacable float cup is disposed between the bonnet and the first seat. The float cup adapted to be sealingly seated against the second seat when the vacuum breaker is subject to an open flow condition, and to be sealingly seated against the first seat when the vacuum breaker encounters a pressure loss condition. Gaskets are provided to enhance the seal at the first and second seats. Both seats are above a water level within the body of the vacuum breaker. At the open flow condition the float cup seals the air vent and at the pressure loss condition the float cup opens the air vent.