In the process of making cement one of the tools that must be maintained its operational stability is vertical roller mill. Its function is as a tool crusher clinker material and other additives by using 3 pieces of roller mill that is above the rotary table rotating clockwise. In the operating system there is a water injection that spray water with a discharge of 2-5 m3 / hour that serves to stabilize the material located on the rotary table and will be destroyed by a roller mill (grinding bed). Vertical Roller Mill often stops due to vibration. One of the causes of vibration is failure of operation on water injection so that water requirement for vertical roller mill is not sufficient. This is because the water supply in the tank is exhausted resulting in the unstable of grinding bed material in the rotary table and overheating of the vertical roller mill due to overheating clinkers. The effect is high vibration and can make vertical roller mill stop working. The cause of the vacuum of the storage tank generally occurs during the process of filling the water into the tank that still uses the manual valve, so there is a risk of negligence for the production patroller in maintaining the water level in the tank periodically. The purpose of this paper is to design and apply the automation of water filling system in the water injection tank. By installing a level sensor and a control valve, it acts as an upper and lower position limiting as an indicator for the control valve when making a decision to open or close the valve. The result of water tank system automation is to maintain water availability in the water injection tank so as to reduce the vertical frequency of the roller mill stop and to make efficient use of water