The Green-Ampt and Philip infiltration models are simplified with a capillary tube representation of porous media that can predict wetting front movement during horizontal and vertical infiltration into dry or initially moist soil. The simple model captures the fundamental physics of unsaturated fluid flow and reduces the number of parameters that must be measured. The relevant parameters are the air-liquid interfacial tension, the density and viscosity of the liquid, the initial saturation, and the permeability. Comparisons with published data show good predictions for infiltration under nonnegative source pressures but are less successful under negative source pressures. The model applies to imbibition of both water and nonaqueous phase liquids. ¿ American Geophysical Union 1996.