💧 AquaWatch — ESP8266 Water Level Monitor

A self-hosted water tank monitoring system using an ESP8266 and HS-S37P water depth sensor.your device serving a live dashboard on your local network.

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📸 Features

• 4-level water detection using the HS-S37P analog sensor
• Animated tank visualization on a live web dashboard
• Buzzer alert triggers when water reaches Level 4 (top line)
• Full-screen popup alert on the dashboard when tank is full
• Live history chart of sensor readings
• Self-hosted — ESP8266 runs its own web server, no internet needed
• Demo mode — dashboard previews with simulated data when not connected

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🧰 Hardware Required

Component	Details
ESP8266	NodeMCU or Wemos D1 Mini
HS-S37P	Water depth / level sensor
Buzzer	Active buzzer (3.3V or 5V)
Jumper wires	Male-to-female
Power supply	USB or 5V adapter

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🔌 Wiring

HS-S37P Sensor          ESP8266
──────────────          ───────
S  ──────────────►  A0   (analog signal)
+  ──────────────►  3.3V (VCC)
G  ──────────────►  GND

Buzzer                  ESP8266
──────────────          ───────
   +   ──────────────►  D2 / GPIO4
   -   ──────────────►  GND

Note: The HS-S37P has 4 exposed sensing traces. As water rises and bridges more traces, the analog voltage on A0 increases in steps.

🚀 Setup Guide

1. Flash the Firmware

1. Open aquawatch_esp8266.ino in Arduino IDE
2. Install required libraries if not already present:
   • ESP8266WiFi (comes with ESP8266 board package)
   • ESP8266WebServer (comes with ESP8266 board package)
3. Set your WiFi credentials:

   const char* ssid     = "Your_WiFi_Name";
   const char* password = "Your_Password";
   

4. Select your board: Tools → Board → NodeMCU 1.0 (or your variant)
5. Upload the sketch

2. Calibrate the Sensor

The HS-S37P gives a rising ADC value as more of the sensor is submerged. You need to find the ADC value at each of the 4 sensor lines:

1. Open Serial Monitor at 115200 baud
2. Dip the sensor to each line, one at a time, and note the ADC value printed
3. Update the thresholds in the firmware:

#define LEVEL1_MIN   50    // ADC > this → Level 1 (bottom line)
#define LEVEL2_MIN  200    // ADC > this → Level 2
#define LEVEL3_MIN  350    // ADC > this → Level 3
#define LEVEL4_MIN  515    // ADC > this → Level 4 ← buzzer triggers here

These are typical values for a 3.3V supply. Your sensor may vary — always calibrate.

3. Find the Device IP

After flashing, open Serial Monitor. You will see:

AquaWatch — HS-S37P 4-Level Build
───────────────────────────────────
Connected!
IP: 192.168.1.105
Server ready.

Note the IP address.

4. Open the Dashboard

1. Open water_dashboard.html in any browser on the same WiFi network
2. Enter the device IP in the Device IP field (e.g. 192.168.1.105)
3. Click Connect — the dashboard starts polling every second

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📊 How the Sensor Works

The HS-S37P is not a true ultrasonic depth sensor. It works by detecting electrical conductivity between exposed copper traces on the sensor PCB. As water rises:

Water touches...	ADC range (approx)	Level shown
Nothing (dry)	0 – 50	0%
Line 1 (bottom)	50 – 200	25%
Line 2	200 – 350	50%
Line 3	350 – 450	75%
Line 4 (top)	450+	100% 🚨

When Level 4 is reached:

• Buzzer beeps (250ms on / 300ms off pattern)
• Dashboard tank turns red
• Full-screen alert popup appears with an ACKNOWLEDGE button

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🌐 API Endpoint

The ESP8266 serves a JSON endpoint at http://<device-ip>/data:

{
  "level": 600,
  "waterLevel": 4,
  "threshold": 515,
  "percent": 100,
  "isFull": true,
  "status": "FULL"
}

Field	Description
level	Raw ADC value (0–1023)
waterLevel	Detected level 0–4
threshold	ADC value for Level 4 trigger
percent	Percentage (waterLevel × 25)
isFull	true when Level 4 is reached
status	DRY / NORMAL / HIGH / FULL

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⚙️ Configuration Reference

Firmware (aquawatch_esp8266.ino)

Constant	Default	Description
LEVEL1_MIN	50	ADC threshold for Level 1
LEVEL2_MIN	200	ADC threshold for Level 2
LEVEL3_MIN	350	ADC threshold for Level 3
LEVEL4_MIN	450	ADC threshold for Level 4 (buzzer)
BEEP_ON_MS	250	Buzzer ON duration per beep (ms)
BEEP_OFF_MS	300	Buzzer OFF duration per beep (ms)

Dashboard (water_dashboard.html)

Settings are entered directly in the UI:

Field	Description
Device IP	IP address of your ESP8266
Full Threshold (ADC)	Reference ADC value shown in stats

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🛠️ Troubleshooting

Buzzer beeps immediately on power-up → That is intentional — a single short beep on startup confirms the buzzer works.

ADC reads random values / sensor noisy → Add a 10kΩ pull-down resistor between A0 and GND. Also ensure stable 3.3V supply.

Dashboard shows "Disconnected" → Make sure your browser and ESP8266 are on the same WiFi network. Some browsers block HTTP fetch from a local file — try serving the HTML via a local server or use the ESP8266's / page directly.

Sensor degrading over time → The HS-S37P copper traces corrode with prolonged water contact. For longer life, only insert the sensor into water when needed, or coat the non-sensing back side with silicone sealant.

Compilation error: 'D2' not declared → The firmware uses raw GPIO numbers (#define BUZZER_PIN 4) instead of Arduino-style macros to avoid this. If you change pins, use the GPIO number, not the D-label (e.g. D2 = GPIO4, D1 = GPIO5).

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📌 Pin Reference (NodeMCU)

NodeMCU Label	GPIO	Used for
A0	ADC0	Sensor signal (S)
D2	GPIO4	Buzzer (+)

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📜 License

MIT — free to use, modify, and distribute.

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Built with ESP8266 Arduino Core · No cloud dependencies