An alternative procedure to determine the hydraulic conductivity function (k-function) based on relationships between saturated hydraulic conductivity and void ratio and between air-entry value and void ratio is proposed. The procedure was applied to determine the k-function of deinking by-products, a highly compressible industrial by-product that is used as alternative material in geoenvironmental applications. The validity of the procedure is verified by comparing the k-function of a compressible soil obtained based on the proposed procedure (using published experimental data) with experimentally determined unsaturated hydraulic conductivities for the same soil.