Water level sensor strip with ESP32

Supply 3.3-5 V Bus ANALOG Measures water level

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
S	Analog output	D34	Higher voltage means more of the strip is under water. To an ADC pin (prefer ADC1: GPIO 32 to 39)
VCC	Power	3V3	Marked + on the board. Use 3V3
GND	Ground	GND	Marked - on the board

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

void setup() { Serial.begin(115200); }

void loop() {
  int mv = analogReadMilliVolts(34);  // S on GPIO 34
  Serial.println(mv);
  delay(200);
}

Generic water level sensor module, Exposed traces with an NPN transistor, analog output

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.