Mine are basically under every water-using appliance, plus some extra ones in the basement in places where there is a risk of water ingress. I've also built a

Mine are basically under every water-using appliance, plus some extra ones in the basement in places where there is a risk of water ingress. I've also built a sensor (HC-SR04, ESP32, ESPHome, Home Assistant) to monitor the water level in my sump pit so that I can make sure the pumps are working.