A portable negative pressure wound therapy system includes a dressing assembly for positioning over a wound to apply a negative pressure to the wound and a canister assembly. The canister assembly includes a control unit having a vacuum source and a controller and a collection canister in communication with the dressing assembly operable to receive fluid from the wound. The collection canister has a filter assembly having a filter and a passageway between the filter and a wall of the collection canister. The collection canister also includes a canister interface having a suction port, an inlet port, and a channel. The vacuum source draws air through the suction port from the channel which draws air from the passageway connected to the channel, the air in the passageway is drawn from the collection canister through the filter, and the air in the collection canister is drawn through the inlet port.
