an esp8266 (or esp32 if you have on laying around) and a long wire. cut that in half, remove the insulation from the ends, wire one to ground and one to any output pin on the esp. detect when the pin gets shorted (basically a button activated by water).
use esphome and the button input.
an esp8266 (or esp32 if you have on laying around) and a long wire. cut that in half, remove the insulation from the ends, wire one to ground and one to any output pin on the esp. detect when the pin gets shorted (basically a button activated by water). use esphome and the button input.
Probably need to look for less than a short. Water is conductive but not THAT conductive.