Liquid composition for use inside a toilet bowl, system and method for delivering the same

A liquid composition (L) for use inside a toilet bowl (2) comprises: a) from 10 to 60% by weight of a suitable surfactant, b) from 2 to 25% by weight of at least one volatile substance adapted to evaporate at room temperature from the liquid composition (L) and restore said predetermined pressure after each delivering of dosed amounts of said liquid composition (L), c) from 1 to 25% by weight of at least one perfuming substance, and d) balance solvent. Advantageously, the liquid composition (L) according to the invention allows the delivery of dosed and constant amounts thereof at each water flushing independently of both the amount of liquid provided in the container (3) and of the frequency of the flushing operations thanks to the presence of at least one volatile substance adapted to evaporate at room temperature and to restore the pressure in the container (3) after each delivering..