The S_basin ecological conception implies the use of the so called «grey water» (which is produced in the course of shower and sink use) when flushing toilets. Such an arrangement of the product offers to use the version that combines directly sink and toilet in order to save material, pipes and space (e.g. in small hotel rooms, guest water closets etc.). With such an arrangement the «grey water» ― after hands washing and hygienic procedures and after passing pipe gooseneck ― gravitates into waste tank and is later used to flush toilet. Each cycle of flushing is ended with the feed of small amount of tap water in order to clean the surface of toilet. If the water is insufficient for flushing, the tap water is used directly from pipeline. The surplus of «grey water» is flushed to sewage.