The present study examines the sloshing behavior of water filled in square shaped ground supported liquid storage tanks. The study validates the empirical equations available to determine the sloshing parameters namely sloshing frequency and sloshing mass in the first three modes for square tanks without obstruction. Finite element approach is adopted to investigate the effect of centrally placed obstruction in square shaped ground supported water tanks. The FLUID80 element is used to model the liquid with the help of ANSYS mechanical APDL program to evaluate the performance of various configurations of water tanks. The study evaluates the sloshing behavior under the free vibration analysis for four square tanks of dimensions 2, 4, 6 and 8 m. The height to length ratio of the square tanks is varied from 0.1 to 2 in the increment of 0.1. The study develops graphs of sloshing parameters for square tanks with centrally placed obstruction in the first three modes of vibration. The study finally concludes that the central obstruction limits the sloshing mass excited for square tank configurations. The results show the complex nature of sloshing parameters due to the presence of a central rigid square obstruction. The sloshing mass excited decreases due to presence of a central obstruction in the first mode. However, in the second and third mode the presence of obstruction results in the increase in the mass excited as compared to that observed for tank without obstruction condition.