IoT Water Quality Station with pH, TDS and Turbidity Dashboard

Hostels, RO plants and small industries need a simple answer to one question — is this water within limits right now? Lab tests are accurate but slow and infrequent, so contamination events go unnoticed for days. This project builds a continuous monitoring station: a pH probe, a TDS probe, a turbidity sensor and a DS18B20 temperature probe are conditioned and read by an ESP32, which publishes calibrated readings over Wi-Fi via MQTT. A web dashboard shows live gauges, 24-hour trends and a compliance panel against configurable limits, with alerts when any parameter drifts out of range. The project is rigorous about what the probes can and cannot claim: datasheet accuracies are stated, the two-point pH calibration with buffer solutions is a documented buyer-run procedure, and no lab-grade certification is claimed.

1. The pH probe, TDS probe, turbidity sensor and DS18B20 are mounted in the sample chamber and wired to the ESP32 through their conditioning modules.
2. Firmware reads each channel, applies the stored calibration coefficients, and converts raw ADC values to pH, ppm, NTU and degrees Celsius.
3. Every 60 seconds (design target) the ESP32 publishes a JSON payload with all four parameters over Wi-Fi via MQTT.
4. The dashboard stores the series and renders live gauges, 24-hour trend graphs and the compliance panel.
5. When a reading crosses its configured limit, the alert service flags the dashboard and writes an event to the log with value and duration.
6. The buyer runs the two-point pH calibration with buffer solutions and records the slope and offset; the procedure and expected values are in the manual.
7. Daily summaries (min/max/average per parameter) are computed for the report and the dashboard's history view.

Tech stack:

• ESP32 development board
• pH probe with conditioning module
• TDS probe with conditioning module
• Turbidity sensor module
• DS18B20 temperature probe
• MQTT broker + web dashboard
• Arduino IDE (C/C++ firmware)
• pH 4.0/7.0 buffer solutions (calibration)

• [Four-parameter sensing] pH probe, TDS probe, turbidity sensor and DS18B20 temperature probe give a complete basic quality picture, each read through its own conditioning stage.
• [Live web dashboard] Gauges, 24-hour trend graphs and a compliance panel show current values against configurable safe limits, demonstrated with real water samples.
• [Compliance alerts] When pH, TDS or turbidity crosses its limit, the dashboard raises an alert and logs the event with the offending value and duration.
• [MQTT telemetry] The ESP32 publishes calibrated JSON readings over Wi-Fi via MQTT on a configurable interval with a 60-second design target and reconnect handling.
• [Documented calibration] Two-point pH calibration with 4.0/7.0 buffer solutions and a TDS check against a reference solution are buyer-run procedures in the manual.
• [Sample chamber rig] Probes mount in a small flow-through sample chamber on the prototype so demonstrations use real water, not dry probes on a bench.
• [Data export] The dashboard exports the reading history as CSV for the report's analysis section.

• Working water quality station prototype (4 probes, conditioning, ESP32, sample chamber)
• Complete firmware source (reading, calibration math, MQTT telemetry)
• Live web dashboard (gauges, trends, compliance, alerts) demonstrated with water samples
• Circuit and wiring documentation
• Buyer-run calibration manual (pH buffers, TDS reference, expected values)
• Component list with ratings
• Project report PDF (water quality background, sensor principles, IoT architecture, methodology)
• PPT presentation for final review
• Viva Q&A preparation document (pH measurement, TDS, turbidity, MQTT, calibration)
• Setup and demonstration guide

• Probe accuracies are module-grade (approximately +/-0.1 pH after calibration, expected); this is a teaching station, not a certified lab instrument.
• pH probes drift and need recalibration every few weeks; the procedure is documented but recurring.
• Turbidity readings are indicative — the sensor is not a nephelometer and suspended solids vary with particle type.
• The station monitors continuously but does not purify or treat water; it is a monitoring build only.
• Probes must stay wet in storage solution between demos; dry storage shortens probe life.