Considering the damages caused by past earthquakes on the reservoirs and the seismic analysis performed on them, designing more earthquake-resistant reservoirs seems to be essential. In this study, the inner radius of the modeled reservoir is considered to be 24 meters and its outer height is 6 meters. The thickness of the floor, wall and roof is determined to be 300 mm. Also, in this study, three different fluid levels are used, with a volume percentage of 50, 75 and 90 percent of the reservoir capacity filled with water, respectively. Modal analysis shows that with increasing water level inside the reservoir, the percentage of total mass participating in the first and second cases increases. The results also show that with increasing volume occupied in the reservoir, the periodic period also increases. The responses studied include the hydrodynamic pressure caused by the fluid on the reservoir wall and structural forces including radial force, bending moment and shear force. So that for a tank with a filled volume, the pressure values are 473 KN/M, 3.46 KN/M, and 5.33 KN/M, respectively. In the turbulent state, these values are 153 KN/M, 9.12 KN/M, and 5.10 KN/M, respectively. The effect of the fluid level on the height of the oscillations shows with an increase in the water height from 50 to 90 percent, this value increases by approximately 30 percent. Also, with an increase in the fluid level from 50 to 75 percent, the slope of the curve increases by 22 percent. Changing the fluid level from 75 to 90 percent also causes an 89 percent increase in the base shear slope compared to the previous state. Examining the effect of the fluid level on changes in environmental forces shows that there is a nonlinear relationship between the percentage of the filled volume environmental forces.