This study provides insight into liquid percolation through the pores of a porous medium such as the Gas Diffusion Layer of a PEM fuel cell. The variety of pore sizes and geometries corroborated with mixed wetting properties contribute to complex transport features which are only marginally understood and controlled. The percolation pressure required for liquid protrusion through a pore is a strong function of geometry and pinning characteristics, as evidenced by numerical simulations of the process. These results show an alternative view to the capillary tube model and sheds light onto the evolution of the gas-liquid interface as the liquid passes through the pore. Geometrical and pinning features need to be included in an accurate pore model, a better understanding in this direction can aid in the development and characterization of porous materials for energy applications and beyond.