A liquid-collection canister for collecting liquid from a tissue site to which reduced pressure treatment is applied, the canister comprising: an outer shell ; an inner liner positionable within the outer shell such that at least one gas-communication pathway is created between the inner liner and the outer shell , the inner liner defining a liquid collection chamber , the inner liner further including at least one aperture to allow gaseous communication between the liquid collection chamber and the gas-communication pathway ; and a liquid air separator positioned over the at least one aperture to substantially prevent liquid passing through the aperture , characterised in that :- the outer shell is substantially rectangular prism shaped; the inner liner includes a plurality of walls and is substantially rectangular prism shaped; the at least one gas-communication pathway further comprises a first gas-communication pathway and a second gas-communication pathway, the first gas-communication pathway positioned between a first wall of the plurality of walls and the outer shell , the second gas-communication pathway positioned between a second wall of the plurality of walls and the outer shell ; the at least one aperture further comprising a first aperture and a second aperture, the first aperture disposed in the first wall between the first gas-communication pathway and the liquid collection chamber , the second aperture disposed in the second wall between the second gas-communication pathway and the liquid collection chamber . an outer shell ; an inner liner positionable within the outer shell such that at least one gas-communication pathway is created between the inner liner and the outer shell , the inner liner defining a liquid collection chamber , the inner liner further including at least one aperture to allow gaseous communication between the liquid collection chamber and the gas-communication pathway ; and a liquid air separator positioned over the at least one aperture to substantially prevent liquid passing through the aperture , characterised in that :- the outer shell is substantially rectangular prism shaped; the inner liner includes a plurality of walls and is substantially rectangular prism shaped; the at least one gas-communication pathway further comprises a first gas-communication pathway and a second gas-communication pathway, the first gas-communication pathway positioned between a first wall of the plurality of walls and the outer shell , the second gas-communication pathway positioned between a second wall of the plurality of walls and the outer shell ; the outer shell is substantially rectangular prism shaped; the inner liner includes a plurality of walls and is substantially rectangular prism shaped; the at least one gas-communication pathway further comprises a first gas-communication pathway and a second gas-communication pathway, the first gas-communication pathway positioned between a first wall of the plurality of walls and the outer shell , the second gas-communication pathway positioned between a second wall of the plurality of walls and the outer shell ; the at least one aperture further comprising a first aperture and a second aperture, the first aperture disposed in the first wall between the first gas-communication pathway and the liquid collection chamber , the second aperture disposed in the second wall between the second gas-communication pathway and the liquid collection chamber . <EOS>