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The environment in a rainwater tank is very hostile to electronics. Sooner or later, the high humidity destroys e,g, the plug connections. Here my newest solution to avoid this, using better material, an ultrasonic sensor and a hydrostatic pressure sensor.

Again no rain for 8 weeks. Climate change should encourage us to take better care of our water. To do this, we need to know our water reserves. The water level of a rainwater tank is measured here with an ultrasonic sensor (XL-MaxSonar-WR MB7060) and a hydrostatic pressure sensor (ALS-MPM-2F).

Since 1999 I have had a round concrete rainwater tank (diameter 2.55m) which is one metre underground. It holds 10000 litres. Since 1999 my measuring devices fail regularly. This is because the environment in the tank is very hostile to electronics. Sooner or later, the high humidity destroys the plug connections. Over the years, I have tried to make the connections less vulnerable. Here my current solutions and improvements:

  •  A second sensor:
    The second sensor uses a different physical measuring principle. It helps to control the accuracy of the data.
  • New cables:
    I exchanged the old cat5 cable with 2 Lapp Ölflex Classic 110 PVC signal cable 4x1 mm² (1119204).
  • Better Heat Shrink Tubes:
    The new tubes are double walled, contain glue, have a 3:1 shrink ratio and are water tight.
  • Better connectors:
    AMP Superseal 1.5 Series Connectors. These are water proof (IP 67). You find videos that explain how to crimp them.
  • Self vulcanising tape:
    This helps to seal everything even better against water.
  • Spare sensor:
    A second sensor with connector , tight and ready to replace a defective sensor.
  •  A device to test the sensor:
    To be sure the receiving circuit or the cable are not defective, I need a circuit for a quick check of the sensor.
For the ultrasonic sensor MB7060 I use a serial connection. The hydrostatic pressure sensor ALS-MPM-2F delivers a current. With the help of a resistor and the ADC of a microcontroller we can read the data.

The circuits and information on the software can be found here:

https://www.weigu.lu/microcontroller/rainwater_level/index.html

The software is on github:

https://github.com/weigu1/rainwater_level