Enormous research has been made to meet the water demand either commercial or public via R.C.C (Reinforced Cement Concrete) tank supply, meanwhile minimal researches are made on Overhead Rectangular R.C.C water tanks. Tanks are commonly used as storage structure, which can be either below or above the ground level to store water, liquid petroleum, petroleum products and similar liquids. This project emphasizes on analytical comparison to justify the effectiveness of overhead rectangular water tank for nominal capacity in terms of material feasibility designed by approximate method and IS code method. When compared, several parameters such as moment, direct tension & depth of vertical walls as well as slab got analysed in which IS code method overwhelmed approximate method. IS code method have been proved economical & feasible during design. The elevated tanks are supported on the leveled R.C.C framed staging. The walls of these tanks are subjected to hydrostatic pressure and the base of the tank is subjected to weight of liquid with its self-weight. The base slab performs structural function to bear the weight of water stored and can be designed using Working State Method (WSM).