You managed to take a simple idea and showcase it brilianntly with well crafted levels. The only part I don't like is how sometimes you can't tell what the max and min water levels were, so there was a bit of trial and error, maybe you could have some UI on the left side that shows the player where the max and min would be? With that, and a little tightening of the player controls, this would be a professinal level game.