Air treatment apparatus

An air treatment apparatus comprising:

• an air flow generator that is arranged to generate an air flow;
• a moisture source that is arranged to introduce water vapour into the air flow;
• a body that in use surrounds both air flow generator and the moisture source;
• and
• a water supply system that is arranged to provide water to the moisture source;
• wherein the water supply system comprises a water tank assembly that is separable from the body, the water tank assembly comprising a water tank, a water supply pipe at least partially disposed within the water tank and arranged to convey water from water tank towards the moisture source, and an ultraviolet light source arranged to irradiate the water passing through the water supply pipe with ultraviolet light;
• wherein the water supply pipe comprises a first end, a second end, the second end covered by an ultraviolet transparent window, the ultraviolet transparent window arranged adjacent to the ultraviolet light source, wherein the first end and the water supply pipe is configured to reflect ultraviolet light, and wherein the water supply pipe is arranged such that water from the water tank enters the water supply pipe adjacent to the first end through an inlet and exits the water supply pipe adjacent to the second end through an outlet, the outlet having an aperture in a side of the water supply pipe and a channel that extends tangentially away from the aperture such that the flow of water forms a vortex within the water supply tube;
• and
• wherein the water tank comprises a tank opening and the water tank assembly further comprises a removable tank cap that is arranged to fit over and thereby occlude the tank opening, and wherein the ultraviolet light source and the water supply pipe are provided on the removable tank cap.