The automatic water level monitoring system using an ESP32 microcontroller has been successfully developed. The system utilizes three analog water level sensors installed on three water tanks in three train carriages. The ESP32 microcontroller reads the water level data and transmits it in real time to the Blynk application via a WiFi connection. Each tank is equipped with three physical LED indicators (LOW, MEDIUM, FULL) as direct visual feedback, along with an automatic notification system through the application whenever the water level changes. The test results indicate that the ADC values at empty tanks are 0, while at full capacity they reach 2128 (water tank 1), 2069 (water tank 2), and 2148 (water tank 3). The sensor data are mapped into percentage values and displayed accurately on the Blynk dashboard at 3-second intervals. Automatic notifications are successfully delivered when the water status changes, demonstrating that the system operates responsively and stably. With this system, water monitoring in train lavatories can be carried out efficiently, in real time, and without the need for manual inspection.

Keywords: water monitoring, train lavatory, ESP32, water level sensor, Blynk, microcontroller.