AC water sensor for electrolysis
Use a sump pump style switch
You build a vertical rod with a float at the bottom.  The rod has &quot;eye bolts&quot; that let it move up and down but not sideways. The rod carries the motion quite far from the corrosive electrolyte.  Note the rod, channel and float can be plastic or fiberglass-epoxy. That linkage can then operate a switch.  If need be, it can carry a magnet near (or away from) a reed switch.
I like the magnet/reed switch option because you can drown that in epoxy to protect it from the electrolyte.
Do not attempt to switch AC power. Since you have DC power anyway, use low voltage DC power out to the switch, and have it operate a quality UL-Listed relay that switches mains power in a way supported by your local Electrical Codes.