A maker in India called Jumpor built an ESP32-based controller that automates rooftop water tank filling, a chore that typically requires manual pump operation and wastes water by running until overflow confirms the tank is full.
The system pairs an ESP32 microcontroller with an ultrasonic level sensor mounted inside the rooftop tank. When water drops below a set threshold, a relay triggers the lift pump. When the sensor reads full, the pump cuts off. No overflow, no waste, no manual intervention. The full write-up on Instructables details a critical edge case: if the sensor reads below its minimum detection range, the controller can misfire and cause the overflow it was built to prevent.
The installation detail is worth reading in full. Jumpor is in a rental, so permanent modifications were off the table. The solution: a replacement tank cap machined to house the sensor and electronics, with the original cap kept for swap-out. It is a clean constraint that forces better engineering, and the documented sensor dead-zone handling alone makes this a useful reference for any level-sensing build.
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