A suction canister assembly comprises an enclosed receptacle having a first opening for providing suction to the receptacle and a second opening for drawing fluids, including liquids and gases, into the receptacle during suction. A unitary shut-off valve/filter element is associated with the interior side of the first opening. This element is oriented within the receptacle so as to be contacted by liquid in the receptacle which rises therein. The element is porous and is adapted to filter particulate matter from gas passing therethrough. In addition, the valve/filter element is capable of developing sufficiently high surface tension under liquid contact to serve as a barrier against liquid passage therethrough at pressure differentials across the element when vacuum is applied on one side of the element. As a result, the element is adapted to terminate suction through the suction opening when liquid rises in the receptacle to completely cover the element.