In industry, the water level control problem is a typical process control problem, and has been extensively studied in the literature. This report focuses on the design and implementation of a PLC-based water level control system. In this project, we have two primary objectives:​ the overall mechanical design of the system, and the PLC system design and implementation. In the mechanical design part, the finite element analysis is performed for the water tank to check the area that has high leaking risk. Additionally, a flow simulation in the water tank is conducted to analyze the effect of the transient pressure on the sensors. On the other hand, the water tank is modeled in Simulink, and simulation results have shown that the PID controller can regulate the water level to the desired position. Finally, the PLC ladder diagram is programmed, and the experimental results have verified the effectiveness of the design.