Is it feasible to sense water level in a plastic container with capacitive sensors on the OUTSIDE of the container? The container concerned will be a heavy gague plastic water storage vessel - perhaps 2 - 3mm thick walls.
I'm thinking of using some strips of 1" copper tape glued to the outside and attempting to sense the change in capacitance caused by the presence of water at that level in the container. I suspect the problem here is tha the change would be too small to reliably detect?
Alternatively I could immerse just one long stainless steel rod in the container as one capacitor 'plate' and using single copper strips on the outside at various levels. Here could energise the external electrodes squentially and measure what comes back on the stainless steel rod relying on the conductivity of the water to form the other 'plate'
I need to sense multiple levels and drilling holes in the container is not really an option.
I'm not after a commercial solution, just a quick and dirty DIY approach.
Your thoughts gratefully appreciated.