Cleaning water dispensing system for a toilet with bidet functions, the cleaning water dispensing system comprising a water dispensing nozzle for anal and/or perineal cleaning, wherein the nozzle comprises a body provided with a plurality of water outlet conduits (3, 4, 5) able to dispense a predetermined flow (Q A, Q B) of cleaning water through the body of the nozzle, characterised in that the system further comprises a diaphragm membrane for selective regulation of water outlet through said water outlet conduits (3, 4, 5), wherein said diaphragm membrane is housed in an inner cavity of the body of the nozzle so as to define; ▪ a first distribution chamber of a first predetermined flow (Q A) of cleaning water, the first distribution chamber being provided with an orifice of water inlet from a first water inlet conduit of the body of the nozzle dispensing the first predetermined flow (Q A), said first distribution chamber comprising at least one water outlet orifice communicating with at least one water outlet conduit of the water outlet conduits (3, 4, 5); and ▪ a second distribution chamber of a second predetermined flow (Q B) of cleaning water, the second distribution chamber being provided with an orifice of water inlet from a second water inlet conduit of the body of the nozzle dispensing the second predetermined flow (Q B), said second distribution chamber comprising at least a first and a second water outlet orifices communicating with their corresponding cleaning water outlet conduits (4, 5) of the water outlet conduits (3, 4, 5); wherein said diaphragm membrane is configured and arranged inside the cavity of the body of the nozzle such that it is able to selectively regulate water outlet through at least one of the water outlet conduits (3, 4, 5) of the nozzle; ▪ by said diaphragm membrane coming into contact with the first water outlet orifice of the second distribution chamber to prevent passage of the second predetermined water flow (Q B) through said first water outlet orifice, while water passage through the second water outlet orifice remains open for the second predetermined water flow (Q B), due to the effect of the first predetermined water flow (Q A) entering the first distribution chamber and acting on the diaphragm membrane, and; ▪ by, in the absence of the first predetermined water flow (Q A) entering the first distribution chamber said diaphragm membrane being deformed/displaced due to the effect of the second predetermined water flow (Q B) entering the second water distribution chamber and acting on the diaphragm membrane to allow passage of the second predetermined water flow (Q B) through the first water outlet orifice, while said diaphragm membrane simultaneously closing the water passage of the second predetermined water flow (Q B) through the second water outlet orifice of the second water distribution chamber. ▪ a first distribution chamber of a first predetermined flow (Q A) of cleaning water, the first distribution chamber being provided with an orifice of water inlet from a first water inlet conduit of the body of the nozzle dispensing the first predetermined flow (Q A), said first distribution chamber comprising at least one water outlet orifice communicating with at least one water outlet conduit of the water outlet conduits (3, 4, 5); and ▪ a second distribution chamber of a second predetermined flow (Q B) of cleaning water, the second distribution chamber being provided with an orifice of water inlet from a second water inlet conduit of the body of the nozzle dispensing the second predetermined flow (Q B), said second distribution chamber comprising at least a first and a second water outlet orifices communicating with their corresponding cleaning water outlet conduits (4, 5) of the water outlet conduits (3, 4, 5); wherein said diaphragm membrane is configured and arranged inside the cavity of the body of the nozzle such that it is able to selectively regulate water outlet through at least one of the water outlet conduits (3, 4, 5) of the nozzle; ▪ by said diaphragm membrane coming into contact with the first water outlet orifice of the second distribution chamber to prevent passage of the second predetermined water flow (Q B) through said first water outlet orifice, while water passage through the second water outlet orifice remains open for the second predetermined water flow (Q B), due to the effect of the first predetermined water flow (Q A) entering the first distribution chamber and acting on the diaphragm membrane, and; ▪ by, in the absence of the first predetermined water flow (Q A) entering the first distribution chamber said diaphragm membrane being deformed/displaced due to the effect of the second predetermined water flow (Q B) entering the second water distribution chamber and acting on the diaphragm membrane to allow passage of the second predetermined water flow (Q B) through the first water outlet orifice, while said diaphragm membrane simultaneously closing the water passage of the second predetermined water flow (Q B) through the second water outlet orifice of the second water distribution chamber.