The present invention provides an apparatus (10, 30, 120, 170) for humidifying breathable gas including at least one humidifier part (12, 18, 36, 38, 40) configured to retain a body of liquid therein and defining at least one chamber (14, 16, 74, 76) therein, an inlet (22, 32) communicated with an interior of the at least one humidifier part (12, 18, 36, 38, 40) and connectable to a blower outlet, and an outlet (24, 34) communicated with the interior of the at least one humidifier part (12, 18, 36, 38, 40) and connectable to a patient supply conduit. The at least one chamber (14, 16, 74, 76) is arranged such that liquid from the body of liquid is prevented from exiting the at least one humidifier part (12, 18, 36, 38, 40) through the inlet (22, 32) thereof when the at least one humidifier part (12, 18, 36, 38, 40) is rotated from a working, upright orientation.
