It does not use electricity or batteries to read the temperature. It reads the temperature due to the pressure of the water force

° Digital LED screen to show realtime water temperature

° Temperature range kawaida

° Accuracy to read temperature

° Water-flow powered (they don't use battery)

°360° rotating display for easy viewing

° Auto ON/OFF starting or off water

° Celsius/Fahrenheit switching

° Color indicators:

                 > Blue → cold water

                 > Green → normal

                 > Red → very hot water