Where does the water that flows from the tap come from? And where does it go? Why should we actually save water? These are questions that children often ask, and sometimes their parents give evasive answers because they don't know the exact details. But the water droplet Trixi, who suddenly appears on Flo's sink, knows the answers. He takes the boy on an exciting and sometimes dangerous water journey, where he can see for himself what happens in the sewer, at the treatment plant, and in the water purification facility. In the end, Flo understands where tap water comes from and why he should handle it carefully. An informative book for elementary school children, filled with numerous illustrations and an engaging read.