A humidifier assembly for a CPAP apparatus includes a liquid storage container configured to hold a body of liquid. The liquid storage container includes a humidifying region above a metallic heat conducting material, the humidifying region being a region inside the liquid storage container in which the liquid is evaporated into pressurized respiratory gas generated in the CPAP apparatus. The humidifier assembly further includes a base unit configured to a) receive the liquid storage container and b) connect to a CPAP unit of the CPAP apparatus. The base unit includes a housing providing a base portion to support the liquid storage container thereon, the base portion including a heating element configured to contact the heat conducting material of the liquid storage container when the liquid storage container is supported on the base unit. The base unit also includes an inlet configured to receive and be coupled to an outlet of the CPAP unit. In addition, the liquid storage container is removable from the base unit.