A flexible, saclike bottle, usually made of rubber, intended to be filled with hot water and placed on some part of the body for heat therapy, or simple warming
An apparatus, usually fuel burning, electric or solar powered, in which water is heated to be used directly as domestic hot water or process hot water (but not for supplying space heating, calorifiers etc, for which a boiler or furnace is used)
Water used, in any type of building, for domestic purposes, principally drinking, food preparation, sanitation and personal hygiene (but not including space heating, swimming pool heating, or use for processes such as commercial food preparation or clothes washing)