A structure has a drawer defining at least one chamber receiving a washing agent and is mounted to move in a shell between an extracted position, in which the chamber is accessible from the outside for receiving a washing agent, and a retracted position, in which the chamber is closed by the shell and suited to dispense the washing agent. A passage communicates with the chamber and outside. A pumping member is suited to push a quantity of washing agent from the chamber towards the passage. An actuator operates the pumping member and is fixed on the shell separate from the drawer. The pumping member is able to assume an active condition, coupled to the actuator and to the passage, when the drawer is retracted. The pumping member is able to assume an inactive condition, uncoupled from the actuator or from the passage, when the drawer is extracted.