1.As the built-in device generating electricity without the battery and any other power，connets to water LED will emit the light.
2.When water flows the led lights up instantly
3.Lights up:
  Green when water temp is below 32° C
  Blue when water temp is between 33° C - 41° C
  Red when water temp is between 42° C - 45° C
  Red flashing when water temp is above 45° C
Changes color by detecting water temperature
Water pressure activates the light source
Light goes off when water source is turned off