Abstract: A breathing apparatus of the kind having a water chamber in which a heating element is immersed, the temperature of said element being controlled so that air drawn over the heated water is maintained at or close to a required humidity and temperature at an outlet, the volume of the air passing through the apparatus being substantially greater than that required for breathing and being directed into a face mask connectable to the outlet which is formed with vents through which excess moist/heated air together with air exhaled by a user can pass to atmosphere, is characterized in that the casing for the apparatus is in two parts, comprising a base and a removable housing, in that the base accommodates a water tank, and has a column extending upwards therefrom which defines an air path from the water tank in that the face mask is connected to the upper, outlet end of the column, and in that the heating element is carried by and projects from said removable housing such that it is immersed into the water of said