Abstract: The toilet discharge system includes a valve with a body (1) and a shutter member (2), and an unblocking apparatus for the shutter member which acts to displace the shutter between the closing position and an auxiliary position and to return it subsequently to the closing position. Advantageously, the shutter member is a rotating element, and its displacement takes place along the direction of its rotation axis; the unblocking apparatus can include a pneumatic system which injects air into two chambers (6, 7) defined between the valve body (1) and the shutter member (2), on two opposite sides of the latter. The method of operation consists in submitting the shutter member of the valve to a cycle which includes a displacement between the closing position and an auxiliary position, and subsequent return to the closing position. The shutter member is thereby prevented from becoming blocked, by avoiding formation of scale of lime and the like, and lubrication and cleanliness of the valve are improved.