A water distributor for an automatic laundry or dishwashing machine, comprises a water inlet that is controllable by a programming device of the machine and a movable element controllable by said programming device which serves for supplying water to a predetermined detergent dispenser for carrying a selected detergent towards the washing tub according to the washing program of the machine. The movable element is driven through a shape memory alloy wire electrically connected to a drive circuit that is part of the programming device.