Humidifier reservoir

Disclosed is a water reservoir for a CPAP ventilation or respiratory apparatus for humidifying a flow of breathable gas that reduces the production cost while providing adequate heat transfer to the water volume of the reservoir. The water reservoir 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 film comprising a non-metallic material, and the film includes a wall thickness less than a wall thickness of walls of the reservoir base, with an outer side that engages the heater plate.