Thanks for the replies. My thought was that I could possibly use an interrupt to wake from 'deep sleep' using the LowPower library. I'm mainly trying to optimize battery life. The timing isn't super sensitive, it just needs to detect the water in about 10-20 seconds.
As mentioned, perhaps an interrupt isn't necessary. I can probably just go into deep sleep for a while, and wake up periodically. It looks like LowPower.DeepSleep(milliseconds) would do the trick. I'll probably need to do some tests and check power consumption.
Wawa:
I would think the voltage would decrease if you would do that,
unless you use two different metals and the water is acidic.
Did you use intenal pull up on the pin (assuming the MKR has that), or an external pull up resisor.
Leo..
In my tests, I used an external pull-down resistor. When not submerged, it read 0 volts. When submerged, it read around .5 volts (if I recall correctly.)