A computer approach to the optimal design of elevated INTZE water tank is presented. The resulting to optimum design problems are constrained with non-linear programming problems. Parametric studies with resulting to different capacity of tank and grade of concrete have been carried out. The result of optimum design for INTZE water storage tank have been compared and conclusions drawn. For the minimum capacity and cost of the elevated circular water storage tank the following design variables are chosen as thickness of the cylindrical wall (X1), depth of the floor slab (X2) and depth of the conical floor beam (X3) and thickness of the bottom spherical dome(X4).The Constraints for the optimization are considered according to Standard Specifications. The optimization problem is characterized by having a combination of continuous, discrete and integer sets of design variables. The computer program is written in MATLAB.