After stripping off an oxygen atom how'd ya get the H2 to combine with the leftover O?
This seems to be the way water is formed in the universe:
Scientists have found out what happens to oxygen in space, and it's in short supply there, as it's tightly bound to stardust.now.northropgrumman.com
It is formed naturally. But H2 naturally exists as an element. Though it is highly reactive. Thus, you can react H2 + O2 -> 2H2O