Honestly, I've always thought it would be neat if water had a color. Water should be that lovely aqua-green color you see in the Caribbean. When you pour it into a glass, it shouldn't have any of this clear colorless nonsense. It would be a beautiful blue-green color, and when you drank it the water would be fresh and appetizing.
But on every full moon, all the water in the world should turn dark red, like blood. It would be so creepy and so cool. You'd be sitting there on the porch watching the sunset, and you'd reach for your glass of aquamarine refreshment and the moon would rise and poof! your water would suddenly look like a glass of red wine.