A simple Python program for Raspberry Pi that initiates a pump to deliver water from a reservoir when a water sensor reading returns a value indicating that the water level is running low

auto_topoff.py

import RPi.GPIO as GPIO
import time

WATER_SENSOR_PIN = 23
RELAY_CONTROL_PIN = 27

GPIO.setmode(GPIO.BCM)
GPIO.setup(WATER_SENSOR_PIN, GPIO.IN)
GPIO.setup(RELAY_CONTROL_PIN, GPIO.OUT)


def water_level_low():
    if GPIO.input(WATER_SENSOR_PIN):
        return False
    else:
        return True

def toggle_water_pump_on():
    GPIO.output(RELAY_CONTROL_PIN, GPIO.LOW)

def toggle_water_pump_off():
    GPIO.output(RELAY_CONTROL_PIN, GPIO.HIGH)

def top_off_water():
    if water_level_low() != True:
      print("water level is good")

    else:
      startTime = time.time()

      print("Water level is low; turning pump on")
      toggle_water_pump_on()

      while water_level_low():
        print("Topping off")
        time.sleep(0.01)

      print("Water level topped off; shutting pump off")
      toggle_water_pump_off()

      stopTime = time.time()
      runTime = stopTime - startTime
      print("Pump ran for %.2f  seconds" % runTime)

try:
  while True:
    top_off_water()

    time.sleep(5)
except KeyboardInterrupt:
    print("Keyboard interrupt")
except:
  print("unexpected error")
finally:
  print("cleaning up")
  GPIO.cleanup()

auto_topoff_bom.md

Hardware BOM

• Raspberry Pi
• Water level sensor
• 5v Relay Module
• DC 12V Submersible Water Pump