Humidifier reservoir

A water reservoir for an apparatus for generating a humidified flow of pressurized breathable air for delivery to an entrance of the airways of a patient for respiratory therapy, the water reservoir comprising:

• a reservoir base comprising side walls forming a cavity configured to hold a predetermined maximum volume of water to be used for humidification of the pressurized breathable air,
• wherein the reservoir base further comprises a flange projecting inwardly from at least one of the side walls towards the cavity and forming at least a portion of an opening into the cavity, and wherein the reservoir base further comprises a lip along at least a portion of a free end of the flange,
• wherein the lip extends substantially perpendicular to the flange;
• a reservoir lid pivotally connected to the reservoir base to allow the water reservoir to be movable between an open position and a closed position, the reservoir lid comprising a first opening and a second opening;
• and
• a seal configured to sealingly engage the reservoir lid and the reservoir base when the water reservoir is in the closed position,
• wherein the seal is provided attached to the reservoir lid to move with the reservoir lid between the open position and the closed position,
• wherein the flange forms a sealing surface configured and arranged to engage the seal when the reservoir lid is in the closed position, and
• wherein the sealing surface and the seal are configured and arranged to disengage from one another when the reservoir lid is in the open position.