Smart Monitoring Water Tank (SMWT) is a project undertaken aims to resolve problems of water wastage. This is because excessive use of watered nowadays is very worrying as water consumption unplanned, wasteful and attitude is one that is not responsible. This system of Smart Monitoring Water Tank is produced to overcome the problems that often occur in schools, homes and especially in the mosque. We can see the use of water in the mosques, especially the use of water for ablution (Wudu’) in the water tank is not so controlled. Here is a simple versatile project which indicates the level of water and automatically controls it by using Arduino UNO and Ultrasonic Sensor Module. With this project, the water in the tank can be monitored through this system. If it is marketed, the project was able to put themselves in the business sector and internationally. In addition, it is also can facilitate the work and reduce water wastage.