Abstract: Toilet Flushing system using compressed air (1) is thoroughly automated, run by a PLC, operable just by the pressing of a single button, self-cleaning, which saves water for the waste expel from the toilets as well as working force and chemical products for cleaning them, which uses compressed air for expelling the waste and contaminated waters in replacement for the great amount of water submitted to the gravity force and is operated in expel-replacement cycles of the toilet hydro seal, object of this patent, is consisted of the most effective and radical devices that save the toilets flushing water. As the waste expelling and the hydro seal replacement in the conventional toilets can only be performed by the jet of a large amount of water, they are fundamentally great wasters of water.