A system for treating a tissue site on a patient with reduced pressure, the system comprising: a treatment manifold for deploying proximate to the tissue site; a sealing member for forming a fluid seal over the treatment manifold and a portion of the patient's epidermis; a reduced-pressure source for providing reduced pressure; a reduced-pressure delivery conduit (120, 140) for fluidly coupling to the treatment manifold and to the reduced-pressure source, the reduced-pressure delivery conduit (120, 140) for delivering treatment-reduced-pressure to the treatment manifold; a reduced-pressure assessment conduit for fluidly coupling to the tissue site; an assessment chamber for fluidly coupling to the reduced-pressure assessment conduit for receiving an assessment-reduced-pressure from the tissue site, wherein the assessment chamber comprises a sealed enclosure having a first moveable portion on a wall and wherein the first moveable portion is operable to move under the influence of reduced pressure; and a first pressure detector proximate to the first moveable portion of the assessment chamber and fluidly isolated from the assessment chamber, the first pressure detector operable to sense displacement of the first moveable portion; a fluid reservoir for receiving fluids from the tissue site, wherein the fluid reservoir is fluidly coupled to the reduced-pressure source and the reduced-pressure delivery conduit, characterised in that the fluid reservoir has a second moveable portion on a wall; and a second pressure detector proximate to the second moveable portion of the fluid reservoir and fluidly isolated from the fluid reservoir, the second pressure detector operable to sense displacement of the second moveable portion. a treatment manifold for deploying proximate to the tissue site; a sealing member for forming a fluid seal over the treatment manifold and a portion of the patient's epidermis; a reduced-pressure source for providing reduced pressure; a reduced-pressure delivery conduit (120, 140) for fluidly coupling to the treatment manifold and to the reduced-pressure source, the reduced-pressure delivery conduit (120, 140) for delivering treatment-reduced-pressure to the treatment manifold; a reduced-pressure assessment conduit for fluidly coupling to the tissue site; an assessment chamber for fluidly coupling to the reduced-pressure assessment conduit for receiving an assessment-reduced-pressure from the tissue site, wherein the assessment chamber comprises a sealed enclosure having a first moveable portion on a wall and wherein the first moveable portion is operable to move under the influence of reduced pressure; and a first pressure detector proximate to the first moveable portion of the assessment chamber and fluidly isolated from the assessment chamber, the first pressure detector operable to sense displacement of the first moveable portion; a fluid reservoir for receiving fluids from the tissue site, wherein the fluid reservoir is fluidly coupled to the reduced-pressure source and the reduced-pressure delivery conduit, characterised in that the fluid reservoir has a second moveable portion on a wall; and a second pressure detector proximate to the second moveable portion of the fluid reservoir and fluidly isolated from the fluid reservoir, the second pressure detector operable to sense displacement of the second moveable portion.