Abstract: A water-saving system for the management and disposal of liquid, semi-solid and solid wastes is described that comprises an open-rim toilet bowl for allowing the flow of greywater containing food residues, small pieces of soap, soapy water, toothpaste residues, shaving residues, hair and the like, without allowing the formation of obstructions throughout the length of the open rim; an anti-sedimentation tank placed above and connected to the toilet bowl, said anti-sedimentation tank being capable of receiving and storing greywater that will be reused to flush the toilet to clean the toilet bowl and flush the wastes contained therein; a washbasin-shaped tank lid located above and closing the upper part of the anti-sedimentation tank; and mixer valve installed in the washbasin-shaped lid and connected to cold and hot water supplies, where the mixer valve includes a third water supply intake which is also connected to a water outlet of the intake valve of the anti-sedimentation tank by means of a flexible hose.