This paper describes an advection-diffusion mathematical model in facultative ponds of different geometrical domains. The geometrical domains of the facultative ponds are the side (one-dimensional), the plane (two-dimensional), and the space (three-dimensional). The purpose of this paper is to know the numerical simulations of these three advection-diffusion models (1D, 2D, and 3D) using explicit finite difference method. Numerical simulation can be used to evaluate the distribution of pollutant concentrations. The concentration of pollutant tested was same as the concentration of biochemical oxygen demand. The result of numerical simulation showed that more complex the geometrical domain of a facultative pond, the more visible is the process of moving the mass concentration (advection) and mass spread (diffusion) in the facultative ponds.