We played this game. How to play:
We had to fill the hippo 1.liter at a time and guess how many we would fit in. (not a real one lucky, no animals were ingerd) anwser: 5 liters. The hippo is so full that evey time you flush you save 5.liters of water.
He is brushing his teeth to see how much water he wasted if he left the tap on.