Smart Rainwater Harvesting Controller using ESP32

Rainwater harvesting fails in practice for boring reasons: nobody diverts the first flush, the filter clogs silently, and the tank overflows or runs dry because nobody watches it. This controller handles all three automatically. A rain sensor detects the onset of rain; a motorized ball valve first routes the first flush (design target: first few minutes or a set volume) to drain, then a turbidity sensor gates the clean flow into the storage tank — if the water stays dirty, the controller holds the drain route and logs the event. An ultrasonic sensor tracks tank level, stops inflow at full, and a second valve tops up from the mains only below a reserve level. A filter-clog proxy (flow-time vs level-rise comparison) drives a "clean filter" indicator. Every routing decision appears on the LCD and in an SD-card event log.

1. The rain sensor detects rainfall onset and wakes the controller from its idle monitoring loop.
2. The drain-route valve opens and the first flush (configurable minutes/volume, design target) is sent to drain; the LCD counts down the flush.
3. The turbidity sensor samples the incoming flow; once clarity passes the configured threshold, the controller switches the valves to the tank route.
4. If turbidity stays poor beyond the configured window, the controller holds drain routing and logs a poor-quality event.
5. The ultrasonic sensor tracks tank level continuously; at full it closes the tank route, and below the reserve level it opens the optional mains top-up valve.
6. The firmware cross-checks flow time against level rise; a sustained mismatch raises the filter-clean indicator, and all events are written to the SD log.

Tech stack:

• ESP32 development board
• Rain sensor module (conductive plate)
• Turbidity sensor (analog optical)
• Ultrasonic level sensor (JSN-SR04T waterproof class)
• 2× motorized ball valves (5 V) + relay/H-bridge drivers
• MicroSD card module (event logging)
• 16x2 character LCD
• Arduino IDE (C/C++ firmware)

• [Automatic first-flush diversion] A rain sensor triggers a motorized ball valve that sends the initial dirty runoff to drain for a configurable volume/time before opening the tank route.
• [Turbidity gating] A turbidity sensor checks incoming water clarity; if it stays above the configured threshold, the controller holds the drain route and logs a poor-quality event.
• [Ultrasonic tank level management] Non-contact level sensing stops inflow at full, and optionally tops up from mains below a reserve level — no overflow, no dry pump.
• [Filter-clog indication] The firmware compares expected level rise against flow time; a persistent mismatch lights the "clean filter" indicator instead of failing silently.
• [Motorized ball valves] Two 5 V motorized ball valves (drain route and tank route) driven through relay/H-bridge outputs with position feedback by timing.
• [LCD + SD event log] Every routing decision, turbidity reading and valve action is shown on the LCD and written to an SD card for the report's data section.
• [Manual override] Panel buttons force drain or tank routing for demonstration and maintenance, with the LCD reflecting the override state.

• Working harvesting-controller prototype (ESP32, rain sensor, turbidity sensor, ultrasonic level sensor, 2 motorized valves, LCD, SD module)
• Complete firmware source code (rain detection, first-flush logic, turbidity gating, level management, logging)
• Circuit and wiring documentation with valve-driver notes
• Component list with ratings
• Threshold configuration and demo procedure guide
• Project report PDF (rainwater harvesting background, first-flush and turbidity theory, methodology, test procedure)
• PPT presentation for final review
• Viva Q&A preparation document (turbidity sensing, valve control, level measurement)
• Setup and demonstration guide

• The prototype is demonstrated on a scaled tank model with a hose-fed "rain" source; full rooftop plumbing is the buyer's deployment, not part of the build.
• Turbidity thresholds are configurable design values — the sensor needs the buyer's own two-point check (clear vs dirty water) during setup; no lab-grade water-quality claims.
• Motorized ball valves are timed-drive with stall guard, not encoder-positioned; exact intermediate positions are not guaranteed.
• The filter-clog indicator is a proxy metric (flow vs level rise), not a differential-pressure measurement.
• Rain-sensor response depends on droplet contact; very light drizzle may register late.