The invention relates to a recess plate for a membrane filter device, the filter device having a stack of essentially identical recess plates, the recess plates having recesses, and the recesses forming filter chambers between adjacent recess plates of the stack, into which filter chambers a suspension can be supplied on a cake side of the filter cloth, and the suspension can permeate the filter cloth to a filtrate side thereof, such that a solid content of the suspension deposits on the filter cloth as a filter cake, each filter chamber having a moveable membrane, the membrane and the recess plate enclosing a squeezing chamber, the recess plate having an inlet duct for inserting a pressurizing medium into the squeezing chamber, for mechanical pressing out the respective filter cake. The invention further relates to a method for detecting membrane leakage in such membrane filter device.