A breathable gas supply apparatus has a flow generator configured to pressurize a flow of breathable gas and a humidifier base unit configured to be coupled to the flow generator. A water container is configured to be removably coupled to the humidifier base unit and includes an air inlet and an air inlet passage extending into an interior of the water container from the air inlet. The air inlet passage is configured to direct the pressurized flow of breathable gas in a direction that is substantially parallel to a base of the water container. A barrier wall is provided across an outlet end of the air inlet passage and extends downward from the air inlet passage toward the water container base. In addition, a curved wall opposes both the outlet end of the air inlet passage and the barrier wall and extends downward toward the water container base. The breathable gas supply apparatus also includes a connector defining an airflow passage between an outlet of the flow generator and the air inlet of the water container.