The research works on the biological effects of electromagnetic (EM) radiation have increased globally. Computer simulation models were developed to assess exposure of square, rectangular, pyramidal, and cylindrical water containers to microwave radiation at 300, 900, and 2,400 MHz. The development of the models included determination of EM field distribution and the resulting specific absorption rate (SAR) in the stored water. These models employed CST STUDIO SUITE 2014 package to solve EM field equations by applying the finite-difference time-domain (FDTD) method. The effect of frequency, packaging shape, and polarization on SAR induced in water was determined. High electric field and point SAR were obtained over the whole azimuth and elevation angles range in the pyramidal container model. The highest values of SAR were induced in water at the sharp edges of the four water container models. The order of the effect on total SAR and maximum point SAR is cylindrical < square < rectangular < pyramidal model at 300, 900, and 2,400 MHz for both vertical and horizontal polarizations. It can be concluded that the variation in the packaging shape of the containers, polarization, irradiation geometry, and frequency. In addition, the sharp edges of the container models significantly affect the calculation and distribution of electric and magnetic fields and SAR values induced in the stored water, which in turn could cause variations in the non-thermal effects of the electromagnetic fields in the stored water.