The invention relates to an installation for toilets (2) installed in a building and comprising, for each of the toilets (2), firstly a separator device (20) for separating liquid effluent and solid waste, and secondly a transfer device (20) for moving solid waste into a descent tube (21), the descent tube (21) having a plurality of through openings (22) communicating with a plurality of transfer devices belonging to toilets installed on storeys of the building, and enabling solid waste to be taken by gravity to a treatment device positioned at the bottom of the building.