An auxiliary washing device having a bearing structure prearranged to be fastened to the cabinet of a main machine for the treatment of textile items, the auxiliary device comprising - control means, - a tub supported by the bearing structure, - an agitator member mounted movable in the tub for agitating items to be treated, - motor means for driving the agitator member, - a first duct for supplying washing liquid to the tub, - a pump having an intake section, connected in fluid communication to a drain opening of the tub, and a delivery section, connected in fluid communication to a drain duct, wherein the bearing structure comprises a stationary part and a movable part, the movable part being displaceable with respect to the stationary part to enable access to the tub, wherein the motor means and the pump are controllable by the control means for the purpose of carrying out at least one treatment cycle which can be carried out by the auxiliary device, characterized in that the auxiliary device comprises a diverting device operatively interposed between the delivery section of the pump and the drain duct, the diverting device having an inlet, connected in fluid communication to the delivery section of the pump, a first outlet, connected in fluid communication to a second duct to run washing liquid into the tub, and a second outlet, connected in fluid communication with the drain duct, the diverting device being controllable by the control means to assume a first position and a second position in which, respectively, washing liquid leaving the delivery section of the pump is directed towards the tub, through the first outlet and the second duct, or else towards the drain duct, through the second outlet, the control means being prearranged for controlling the diverting device to assume the first position in at least one washing or rinsing step of the treatment cycle, for causing a recirculation of washing liquid in the tub by means of the pump, and to assume the second position in at least one draining step of the treatment cycle, for causing a draining of washing liquid from the tub by means of the pump. - control means, - a tub supported by the bearing structure, - an agitator member mounted movable in the tub for agitating items to be treated, - motor means for driving the agitator member, - a first duct for supplying washing liquid to the tub, - a pump having an intake section, connected in fluid communication to a drain opening of the tub, and a delivery section, connected in fluid communication to a drain duct, wherein the bearing structure comprises a stationary part and a movable part, the movable part being displaceable with respect to the stationary part to enable access to the tub, wherein the motor means and the pump are controllable by the control means for the purpose of carrying out at least one treatment cycle which can be carried out by the auxiliary device, characterized in that the auxiliary device comprises a diverting device operatively interposed between the delivery section of the pump and the drain duct, the diverting device having an inlet, connected in fluid communication to the delivery section of the pump, a first outlet, connected in fluid communication to a second duct to run washing liquid into the tub, and a second outlet, connected in fluid communication with the drain duct, the diverting device being controllable by the control means to assume a first position and a second position in which, respectively, washing liquid leaving the delivery section of the pump is directed towards the tub, through the first outlet and the second duct, or else towards the drain duct, through the second outlet, the control means being prearranged for controlling the diverting device to assume the first position in at least one washing or rinsing step of the treatment cycle, for causing a recirculation of washing liquid in the tub by means of the pump, and to assume the second position in at least one draining step of the treatment cycle, for causing a draining of washing liquid from the tub by means of the pump.