A water reservoir for an apparatus for humidifying a flow of breathable gas includes a reservoir base including a cavity structured to hold a volume of liquid and a conductive portion provided to the base. The conductive portion is adapted to thermally engage with a heater plate to allow thermal transfer of heat from the heater plate to the volume of liquid. The conductive portion includes a thin film comprising a non-metallic material, and the thin film includes a wall thickness less than about 1 mm.
