In this paper, a reinforced concrete elevated water tank, with a capacity of 900 cubic meters and height of 32 meters, has been utilized and subjected to an ensemble of earthquake records. Finite element model has been employed to model elevated water tank system. Fluid-structure interaction for modeling is considered by Eulerian method. Also the behaviors of concrete and steel material were considered to be nonlinear. Seismic responses of the elevated water tank such as base shear force, overturning moment, displacement and hydrodynamic pressure have been assessed for ensemble earthquake records. The obtained result revealed that scattering of responses in range of the mean minus standard deviation and mean plus standard deviation are approximately 60 to 70 percents. Also, responses of elevated water tank are dependent with earthquake characteristics and frequency of elevated water tank. The maximum response of base shear force, overturning moment, displacement and hydrodynamic pressure occurred in different case of vessel filling.