How to make a float water level sensor?

Question

Do it yourself

I need to know the amount of water in an opaque tank. I don’t want to make holes in the tank for the level gauge tube (because this creates a risk of leaks in this place), so I settled on electronic sensors. In stores I found only emergency sensors that open the circuit when a predetermined level is reached. I need to know how much water is left in the tank without opening it. How can this be implemented?

Answer 1

rusautomation.ru/poplavkovye-datchiki-urovnya-vody is not enough?

Answer 2

An automobile fuel sensor in the tank, during disassembly, you can take from 200 to 1000 rubles.