Flooding is a disaster that often occurs in the current residential environment, one of which is in the village of Yos Sudarso Teluk Betung where this village is located in an area close to a river. Floods can occur due to overflowing of water, one of the reasons is the lack of public awareness that still throws garbage in the river. Therefore, a flood warning system technology is needed that can help provide flood disaster information efficiently. One of them is by utilizing internet of things (IOT) technology which can provide data information in the form of height and water discharge. This study aims to monitor the water level as information during a flood. Ultrasonic sensors are used to detect water levels, water flow sensors are used to read water discharge and Arduino uno is used to process and send data to smartphones via the Whatsapp application. The results of this study obtained a system that can monitor the condition of the river water level repeatedly and when it reaches the specified height, the system will send a flood warning using the Whatsapp application that has been installed on the smartphone, the data will be stored in the database and the buzzer as an alarm sign and led lights are used. as an indicator that can inform the status of alert, alert, and danger. With the flood warning detection system is expected to provide information when a flood occurs.