A general Darcy's law based model for batch pressure filtration of particulate suspensions is described. Based on this model, two measurement indices for quantifying dewatering performance using experimental constant pressure filtration data are formulated. Results obtained using these indices are in accordance with existing results. The proposed procedure can be particularly useful in situations where the operating pressure is known, and one is only interested in investigating the effect of chemical additives and their dosage on dewaterability of a given suspension. (c) 2006 Elsevier B.V. All rights reserved.