Among the different shapes available, conical vessels are commonly used as water reservoirs because of their large storage capacities. Motivated by the lack of guidelines available for their analysis and design in the existing codes of practice, this study focuses on analyzing reinforced concrete conical tanks under the effect of hydrostatic pressure. A finite element model (FEM), which accounts for material nonlinearity experienced in reinforced concrete, is developed. This nonlinearity is considered by implementing a concrete plasticity constitutive model in the developed FEM. Analysis of a set of 12 tanks with different practical dimensions is performed under hydrostatic water pressure. The variations of meridional and hoop stresses through the thickness of the tanks are determined by plotting the stresses at the outer faces of the tank’s wall. The effect of including material nonlinearity in the FEM on the deformed shape is assessed. The developed FEM is used to find the location of maximum deflection and stresses. The variations in the maximum deflection and stresses with the dimensional parameters of the conical vessel are reported.