pylon:
Maybe something like this will serve you?http://www.seeedstudio.com/depot/water-level-switch-p-565.html?cPath=156_160
I was looking at vertical floats.
I don't really want to have to cut through the bottom of the water tank because it's just one more hole onto the electronics, but it is a possibility. I need a very narrow float. I have about 25mm to play with at the bottom of the tank.
Also, if the water boils and makes the float switch, it might cut the circuit to the relay controlling the boil. But could be solved with a short timer of the connection time.
I'll think about it.
Thanks