There are two problems that I can see:
You need a separate high-impedance input circuit with a greater-than-1M pullup resistor to sense the water probe, and that in turn switch the reset system.
Also, I believe the reset pin must be pulled low and released to high level again, to restart the MCU from sleep.
That would mean using a schmitt trigger stage from the water detector to produce a fast level transition, then a capacitor-resistor edge edge detector into the reset control.
You could do both with a couple of sections of such as a 4093 or 40106 (or 74HC14) schmitt input gates.
Note that if the water probe will be submersed long term, it will eventually cause some electrolysis and corrosion on such as copper or iron; you would need to use stainless steel probes/contacts to maintain conductivity.