Cpap system

A water reservoir for an apparatus for humidifying a flow of breathable gas to be delivered to a patient, the water reservoir constructed and arranged to removably engage with a heater plate of the apparatus when in a working configuration to provide heat to a volume of water in the water reservoir, the water reservoir comprising:

• a reservoir base including a cavity structured to hold a volume of water when the water reservoir is in the working configuration;
• a conductive portion provided to the reservoir base so as to form at least a portion of the cavity for holding the volume of water,
• wherein the conductive portion is adapted to thermally engage with the heater plate when the water reservoir is in the working configuration to allow thermal transfer of heat from the heater plate to the volume of water in use;
• and
• a reservoir lid movably connected to the reservoir base to allow the water reservoir to be convertible between an open configuration and a closed configuration,
• wherein the reservoir lid comprises an inlet tube arranged to provide an inlet for a flow of breathable gas entering the cavity and an outlet tube arranged to provide an outlet for a flow of humidified breathable gas exiting the cavity,
• wherein the inlet tube includes an inlet end arranged outside the cavity and an outlet end arranged inside the cavity, and the outlet tube includes an outlet end arranged outside the cavity and an inlet end arranged inside the cavity,
• wherein at least one of the inlet tube and the outlet tube changes a parameter at least at one point along its length, and
• wherein one of the inlet tube and the outlet tube is curved at least partially around the other of the inlet tube and the outlet tube.