IoT-Based Smart Water Tank Monitoring System

Manual inspection of domestic water tanks is inefficient, often missing critical drops in water availability. We present an end-to-end IoT stack that couples an HC-SR04 ultrasonic sensor with an ESP32 controller, batches 45 samples (at 1 Hz) every 45 seconds, and authenticates payload delivery through a Supabase Edge Function. A React web dashboard provides historical analytics, configurable alerts, and remote calibration. Bench validation on a 8 cm cylindrical prototype (1.0 L) achieved a 0.63 cm mean absolute error (7.9% of tank height), 320 ms median ingestion latency, 1.6 s dashboard refresh time, and 100 % alert delivery. These results demonstrate that a low-cost architecture can meet residential reliability targets while remaining scalable for multi-tank deployments.