In the current revolution industry era, water is a must for everyone. For water to be available every time, there must be a mechanism for transporting water from one place to another. A water leak is a common problem when transporting water. Based on research in 2018 in Australia, it is estimated that 12% water is lost due to leakage. In some developing countries, the water loss rate can be higher. To find out the location of leakage, monitor about the habit of the system is needed. The common features used to locate leaks are water flow and pressure. Flow is more preferable feature to monitor due to its resistance to interference than pressure. For this purpose, an accurate and practical flow sensor is the Ultrasonic Water Flowmeter TUF-2000. This sensor can obtain a data stream containing water flow data in a pipe. We used the Local Outlier Factor (LOF) Algorithm to detect flow anomalies. The location of the anomaly also can be estimated based on sensor location. Our method can accurately detect sudden flow changes suspected of leak signatures. However, the challenge is the evolutionary flow changes due to small leaks, as this type of leak could result in the evolving outlier detection model.