The kitchen tap works using the water on the fresh water tank.
Check that you have enough water in the tank. A pump running without water can break!
To activate the tap, open the lever slightly and let the water run. The water pump starts automatically as soon as the tap is opened.
Once you are done, make sure to close it properly, otherwise the pump might still be activated, even though there is no water flowing.
The water running down the kitchen sink goes to the waste water tank.
Remember to empty the grey water tank when the camping display indicates is full.
No water flowing? See here!