In earthquake resigns, the elevated water tanks are one of the most important lifeline structures. In major cities & also in rural area, elevated water tanks forms an integral part of water supply scheme. The elevated water tank must functional even after the earthquakes as water tanks are required to provide water for drinking and firefighting purpose. The main object of this paper is, to compare the Static and Dynamic analysis of elevated water tank, to study the dynamic response of elevated water tank by both the methods, to study the hydrodynamic effect on elevated water tank, to compare the effects of Impulsive and Convective pressure results. From detail study and analysis it was found that, for same capacity, same geometry, same height, with same staging system, with same Importance factor & Response reduction factor, in the same Zone; response by equivalent static method to dynamic method differ considerably. However studies on RCC water tank by considering dynamic analysis are very few. Hence, in the present work static and dynamic analysis of RCC elevated water tank carried out with the considering effect of impulsive and convective pressure.