This specific urinal works without flushing water which enables significant savings in its consumption since it is only used occasionally in the cleaning process. For this purpose, the outlet trap is composed of a sealing membrane that prevents odours from escaping and a deodorising ring that guarantees a pleasant aroma. The system is functional, simple and practical. The membrane only allows liquids to enter the drainage system without backflow. When passing through the outlet trap the liquid causes the membrane to open and cloasing immediately afterwards which also prevents the emission of odours from the sewer.