PURPOSE: To make effective purification of bathwater possible for equipment comprising a bathtub and a heating device by a method wherein a purifier equipped with a depurant container housing depurant for purifying bathwater is provided to a suction part of the heating device.

CONSTITUTION: A bathtub 2 and a heating device 3 for heating bathwater are provided, and the heating device 3 is composed of a suction part 4 for sucking bathwater and a feed part 5 that feeds heated bathwater through a passage 6. Then, a bathwater purifier 10 is attached to an opening 8 of the suction part 4 from the bathtub 2 side, and a pocket part 12 for housing a packed depurant is provided to the purifier 10. Therefore, purification of bathwater and elution of effective component can be executed by utilizing natural circulation of bathwater under heating.