Water may have been discovered on Saturn's moon Enceladus, encouraging speculation about the possibility that there may be life there. Slate's Explainer has a good column on how water is related to life. The column has links to sources about the discoveries on Enceladus.
Water has a number of unusual properties. It is the only common substance that exists in gas, water, and solid at common temperatures, and that's important. It is the only common substance with a solid less dense than the liquid -- ice floats. Without water vapor, there would not be rain. Without layers of ice on top of bodies of water, they would freeze solid, but ice insulates. Fish and other organisms in water in cold parts of the earth are able to survive because of this.
Water is transparent. If it were not, we couldn't see -- light comes through the liquid in our eyes, which is mostly water, to the retina at the back of our eyes. If water wasn't transparent, plants couldn't carry on photosynthesis under it, and fish and crustaceans couldn't see. While we're on photosynthesis, water is one of the raw materials plants use to manufacture the food we need by this process. (Using food for energy is mostly the reverse -- re-creating water in our mitochondria.)
Water will dissolve many things. Thus, it is useful in carrying food and other substances in the bodies of organisms.
There are other important and unusual properties of water. Many people suspect that water was specially designed by God. I am one of these. However, this can't be proved.
What are the theological implications of life on other worlds, should such exist? I don't see any particular significance to such a discovery, as such, unless this life is sentient, intelligent, and able to communicate with us. Nowhere in scripture does it say that this is impossible, so far as I know. (Nor does the Bible say unequivocally that life elsewhere exists.) Some science fiction writers (C. S. Lewis, in Out of the Silent Planet and Perelandra, and James Blish, in A Case of Conscience, and probably others) have written about intelligent non-human organisms that have not experienced the Fall. Now that would have some interesting theological implications. So would evangelizing extraterrestrials.
An omniscient creator doesn't need to be bound to have created life on only one world, or on many. Nor is He bound to have created only one kind of life, the Carbon-based life that we know of, requiring water.
The SETI institute is dedicated to finding life elsewhere.
In his Out of the Silent Planet, Lewis criticized the view that humans have a right, or destiny, to spread ourselves to other worlds.