Stress distribution in a confined wet cake is analysed by solving the equation of equilibrium of force acting on the system. An integrated equation is derived to estimate the stress distribution within the cake providing the boundary values around the cell are known. The results are applied to estimate the mean stress acting on the confined cake and also to correct the effect of side-wall friction of the compression-permeability (C-P) cell tests. These corrected data are then used to predict the performance of constant-pressure filtrations. From the results of these predictions, it is indicated that the simulated results based on the corrected C-P cell test data may give an average deviation around 5%, while the simulated results based on the C-P cell test data without correction give a deviation higher than 10%.