The working principle of filter presses is that slurry is pumped into the machine such that solids are distributed evenly during the fill cycle. Solids build up on the filter cloth, forming the filter cake; the filtrate exits the filter plates through the corner ports into the manifold, yielding clean filtered water.

Filter presses are a pressure filtration method and as such, as the filter press feed pump builds pressure, solids build within the chambers until they are completely chock-full of solids, forming the cake. Once the chambers are full, the cycle is complete and the filter cakes are ready to be released. In many higher capacity filter presses, fast-action automatic plate shifters are employed, speeding cycle time. Some filter presses are specifically designed for fully automatic, 24-hour operation in a harsh environment such as mines or chemical manufacturing plants.