Measuring Water level

Capacitive contact less water level sensor.
Help is needed

Dears Engineer’s Asylum member out there, interested in measuring water levels of clean and dirty water in a tank? Help me out.

Measuring water levels itself can be done in different ways, some have done it with TOF ultrasound audio echo’s, you can use sensor rods, pressure sensors can be used. All these methods have one disadvantage, they are in contact with (dirty)water or with the water vapor and that makes that long exposure of these sensors to water or vapor make that they fail overtime.
A sensor based on contactless capacitance is the only sensor that I know that has a chance to survive over a long time because it is not in contact with water or vapor.
Below the picture and math of a contactless capacitor of which the capacitance depends on the water height. The image explains the situation and the expected capacitance values as function of the height.
I want to measure either this capacitance or the converted capacitance to voltage/frequency with a microcontroller.

This is my question:
what is the most simple and effective method to do this. One of the requirements is that no resistors bigger than 1M ohm can be used.

let me know what ideas you have.
Thanks in advance