The tap sensor is one single unit that should be located on the cold water intake pipe in the kitchen.
You can check if the sensor has power by pressing the Circle icon on the front of the sensor in - when pressed firmly, it should make a clicking sound, and the LED above the button should flash once in red.
3. Place the sensor on the cold water intake pipe for the main kitchen tap.
This can usually be found underneath the kitchen sink. Some sinks have mixer taps or combined pipes, in which case any intake pipe where the vibration of water passing through the pipe can be sensed by the sensor should be a fine placement.
As a last resort, perhaps where pipework is concealed or inaccessible, the sensor may be placed on the main body of the tap itself.
Watch our video tutorial below on how to install the tap sensor: