This study develops and demonstrates a model that characterizes defect transports, responsible for water transport within dense ceramics, and calculates the diffusion coefficients for those defects. The multi-species mass transfer processes within yttrium doped barium cerates are modelled by applying the Nernst-Planck equation to the system. The Nernst-Planck equation with suitable boundary conditions is adopted to compute defect diffusion coefficients in COMSOL Multiphysics. All related equations, based on charge and defect conservation, are solved numerically and validated experimentally. The model also predicts the concentration distribution of the defects and potential profiles throughout the membranes. The results provided convenient insights about the water transport and charge distribution as a function of membrane thickness.