You need to understand how our solar system evolved to appreciate from where came water. Mind you, as much as we are covered with water, the mass of our globe is 99.96% solids, with 0.04% being water. These numbers look precise, but these are only best guesses.
- Hydrogen came with the Big Bang.
- Oxygen was created through nucleosynthesis in large stars.
- Combine these two under certain conditions and you have water.
- Remember that our observable atoms in our Universe consist of 90% hydrogen (74% by weight), while oxygen is the #3 element. Water should be abundant everywhere in our Universe.
- Does this mean life is also omnipresent? Well, carbon is the #4 element in our Universe.