A dishwasher (1) programmed to perform at least a washing phase and, subsequently, at least a first rinsing phase and comprising a tub (2) in which the dishes to be washed are placed, a hydraulic circuit (3) for circulating a washing liquid through the tub (2), a dispensing system (10) activable for introducing a flocculant into the washing liquid in the hydraulic circuit (3) in order to promote the aggregation of detergent and dirt particles therein contained for the formation of floes (F); a control unit (11) controlling the operation of the dispensing system (10) and programmed to activate the dispensing system (10) at least at the end of the washing phase, before the first rinsing phase; and separation means (12) for separating the formed floes (F) from the washing liquid in order to render the latter enough clean to perform the subsequent first rinsing phase. By these measures water and energy consumption can be reduced due to reusing the washing liquid.