A system for removing odors from a toilet bowl (I) during its use consists mainly of a blower (2) having its inlet connected to the bowl (I) and its outlet connected to piping (5). The blower (2) is driven by a rotary water motor (15) which is actuated by water entering the initially empty flushing cistern (II). Water from the domestic supply is admitted to the water motor (15) by a valve (3) opened by depression of the toilet seat (7) which is supported on the bowl (I) by a flexible ring (40). The flexible ring (40) serves to seal the gap between bowl (I) and seat (7) and permits downward motion of the seat (7) for opening the valve (3).