system
Given the following post, respond as if you're commenting on Reddit:
human
Is the amount of water on earth always constant, and has it always been that way?

I understand we might find new sources or water reserves, but essentially it would not be "new" water right, just water we hadn't discovered?   Is all the water on earth a remnant from the earth's formation?
gpt
The amount is not constant, though it is practically constant. 

We can get water a couple ways:

When it falls to Earth from space, there is a lot of water vapor and ice floating around up there. 

And, to a much lesser degree, when hydrogen reacts with oxygen this is new water. Every time you burn a hydrogen flame you are creating new water that didn't exist. Though this accounts for much less water than the former process does.

We do lose a bit of water, as particularly energetic water reaches the upper atmosphere and blows away on the solar winds and the like. Though this is currently pretty negligible. 

Overall our total water supply on Earth is pretty stable.