I can't think of many instances where water streams down as in the photo, so cropping out the source (the hint of a faucet) is not an issue to me. There's is just enough there that your mind can figure out the source, but not enough to be a distraction. With the faucet, there is no doubt that this is water. In #2, due the coloring I find myself wondering what that green fluid is, could be anti-freeze or some type of hydraulic fluid or lime flavored Kool-aide for all I know.
As we are all aware, water is one of the basic building blocks of all life, so it fits the "Nature" theme for me. And with the current threats to sustained sources of fresh water, its an even better fit.
#1 would be my pick, followed by #3.