Porous media have many practical applications in the different areas of science. One of these applications is the use of a porous medium in water desalination devices to enhance the heat transfer rate. In this study a modified water desalination device, which consists of a front plate with constant heat flux, porous layer, and a back for heat recovery, is proposed. The natural convection from two vertical plates embedded in a porous medium with variable clearance distance were taken into consideration for maximum water desalination. The governing equations (mass, momentum, and energy), which are partial nonlinear differential equations, were transformed into a set of ordinary differential equations by using the similarity method and solved numerically using the fourth-order Runge-Kutta method. The effects of the clearance distance between the two vertical plates on the temperature distribution and total heat transfer are investigated. It was clear from the results that there is a maximum heat transfer where the two plates are far from each other with eta approximately 16.6, which maximizes the heat recovery process. A minimum heat transfer was achieved when there is no heat recovery from the vapor and the plates were closest to each other (i.e., eta is approximately 4). These analyses show that keeping the separation distance between the plates variable with a maximum at the top of the plates and a minimum at the bottom of the plates of the device will maximize the evaporation rate and thus increases the distilled water.