The paper describes a case of rationalization of the use of the waters of a textile factory located in the northern part of Italy. The water used in the factory comes from deep wells located about 170 m below the level of the factory. The yearly used amount of water is about 540,000 m(3). Inside the factory the water goes to different uses as such for cooling or for general uses or treated as softened or demineralized water where needed. After use the water that has been polluted is sent for biological treatment where takes place a first step of decontamination. Upon exiting the biological treatment, the water quality achieved is not enough for discharge into the open environment; consequently, the water has to be sent for additional external treatment. The complete water cycle has a sizeable cost due to all the existing steps: pumping of all the raw water, internal biological treatment, external after-treatment, and process water treatment by ion-exchange demineralization or softening. Based on all the above, the factory has foreseen a rationalization of the economics of the cycle of the water based on the reuse of part of the waters today sent for discharge. The base of the chosen process is the treatment of part of the water coming from the biological internal treatment as a first step on "innovative" ultrafiltration and as a second step on reverse osmosis. The two treatments positively influence the economics of the ion-exchange treatments in the factory. Pilot tests are currently in progress for fine-tuning.