This paper studies to estimate the dynamic behavior of a demineralized water tank with a piled raft foundation system considering soil-pile-structure-fluid interaction to shock-ground motion. A three-dimensional finite element model of a coupled system is constituted in ANSYS software. Interaction between pile and soil is represented with the frictional contact element. The frictionless contact elements are utilized to model between the water and tank shell to allow for displacement of the free surface adjacent to the tank wall. Shell elements are used for the tank body and its vault. The dynamic analyses of the tank including soil-pile-structure-fluid interaction are presented by using shock response spectra. Ground shock acceleration time histories, generated by using a developed computer program based on Fortran programming language, produce shock response spectra. The effects of the different charge weights and distances from the charge center are examined in the analyses. Also, the effect of the water fill level in the tank and the number of piles is also investigated. The results of the research are presented with the directional displacements and equivalent stresses. It seen from the analyses that the dynamic responses of the tank increase with the charge weight, while decreasing with the charge center distance. Moreover, the water fill level and the number of piles extremely affect the displacement and stress values of the coupled interaction system.