A system for applying a reduced pressure at a tissue site includes a reduced pressure source, a porous pad in fluid communication with the reduced pressure source, and a drape positionable over the porous pad to seal the porous pad at the tissue site. The porous pad includes a plurality of channel walls to form a plurality of channels between the channel walls. The channel walls are substantially liquid impermeable to prevent movement of a liquid through the channel walls but are gas permeable to allow movement of a gas through the channel walls as reduced pressure is applied at the tissue site. The liquid impermeability of the channel walls and the application of reduced pressure causes flow of the liquid to occur through the plurality of channels.