The present invention relates to an apparatus for treatment of sleep disordered breathing, which comprises a flow generator (50) for creating a supply of pressurized breathable gas for delivery to a patient and a humidifier (150) for humidifying the supply of pressurized breathable gas for delivery to the patient the humidifier (150) including a humidifier case with a water-tank-receiving portion, a hinged lid (648), and an elastomeric lid seal (676) attached to the hinged lid (648). A water container is adapted for drop-in assembly in said humidifier case. The water container including an air inlet aperture (801) at an inlet end of an air passage (718). The water container further comprises an air outlet, when the elastomeric lid seal (676) is configured so that closing said hinged lid (648) causes the lid seal (676) to seal against a portion of a top surface of the water container.
