The present invention provides an apparatus comprising a wound dressing (15) connected to a fluid container (11) via a pump (3), wherein the wound dressing is in communication with a mechanical pressure control valve (13), the fluid container is provided with an inlet (2) and an outlet (4). Also provided are (i) flexible fluid containers comprising of at least two layers of film with an integrated vent, (ii) wound dressings and (iii) a multi-compartment wound fluid container (20, 35, 63) comprising at least two internal compartments and provided with an outlet (31, 37, 51) and an inlet (19, 49), in which the container comprises a microporous fluid separator (29, 41, 55) which divides the at least two internal compartments, wherein the microporous fluid separator permits gas flow between the compartments and prevents fluid flow to the outlet of the container. Other apparatus provided comprises a means for detecting the level of fluid within a multi-compartment wound fluid container as described. The invention also provides a system for applying a sub-atmospheric pressure to a wound dressing on a patient using devices and apparatus of the invention and methods of treatment of wounds using such apparatus, devices and systems of the invention.
