I am building a simple water level indicator (approx like the circuit below) for my tank.

However, I am wondering about the wiring, for I suppose copper cables corrode in water and produce toxic result. Looking for a robust non-toxic solution the same.

What wiring is generally used under water?

enter image description here

  • \$\begingroup\$ I don't know the best answer to your question but a capacitive or optical solution likely would not require your conductors be exposed to water. \$\endgroup\$
    – K H
    Jan 9, 2019 at 6:29
  • \$\begingroup\$ anything that has a dc conductor in contact with the water has the potential to leach nasty stuff, though platinum is often used in research. Use AC, so you can insulate the wire and use only capacitance through the insulation, albeit for a slightly more complicated detector. \$\endgroup\$
    – Neil_UK
    Jan 9, 2019 at 6:34

2 Answers 2


The most common solutions are

1) use a float connected to a potentiometer like a petrol/gas tank does https://www.howacarworks.com/fuel-systems/checking-and-replacing-a-fuel-sender-unit

2) use an array of binary float switches, like these, but many other brands available https://www.cynergy3.com/blog/how-select-correct-float-switch

3) to use a circuit like yours with very small AC currents

4) use an optical sensor where the refractive index of the water causes a reflection or not. for example https://www.omega.com/green/pdf/LV170.pdf - many other brands exist

5) use an ultrasonic sensor to measure the height of water in the tank https://www.instructables.com/id/Measuring-water-level-with-ultrasonic-sensor/

6) use a pressure sensor to measure the height of water in the tank as washing machines do http://www.milanocomponenti.com/en/washing/pressure-switches-washing/washing-machine-pressure-switch/


Using a float switch would be your best solution as its designed for these purposes.

Using a bare copper wire requires a lot more current to be pushed through the liquid, this will then in turn cause issues turning on the transistors, so the circuit provided above is ok for 2l containers but if you want to use 5l or larger your will start to experience issues.

Check out RS Components, they have some cool float switches enter link description here


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