Filtration proceeds in a filter press primarily in two stages-filtration and filter-consolidation. Filter-consolidation conforming to the so-called Terzaghis model in soil mechanics is the majar concern in the present piper. A partial defferential equation treating the filter-consolidation as a three-dimensional model

is given as; or where the filter-consolidation coerricient Cv can easily be determined by experimentation. It follows that the filter-consolidation equation is; It is demonstrated that the above eqouation can be applied to constant pressure filter-consolidation in a filter press. Results of high accuracies are claimed.