For sure, you will find oxygen and Hydrogen Then, depending on the geographical zone you are, it might have different minerals among other elements. Let alone if we are talking about filtered ocean water.
Earth is where we live. The planet Earth is in a area of the milky way And we have water on our home planet. The other planets do not have water on them. They might be near galaxies but they are not inside a galaxy
Mercury and Venus are inner planets that does not have water and oxygen. Mars might be another, but we don't know. It might have water. Now Earth....if there was no water and oxygen, I wouldn't be replying to this(except if I was alien, eh?)!
There are theories that the moon use to be part of the Earth, therefore, when the asteroid that hit Earth and sent a large chunk ( Theorized as our moon) in to space, that piece may have water on it from where it use to be part of the Earth.
100% of fresh water is consumable for living organisms. If you mean, what percentage of total water on the Earth is consumable, I believe the figure is somewhere in the region of 3%, but I might be wrong.