Erm, I’m no chemist, but I’m fairly sure you can, with just two ingredients… Has a fairly useful by product too.
I presume you’re referring to hydrogen? Not much of that knocking around (its lighter than air so if there was any then it would leave the atmosphere).
You could argue that burning any hydrocarbon produces water, but that’s also false because that hydrogen got there via photosynthesis from water in the past so is just on a very slow path through the water cycle too.
So yea, in a roundabout way unless you can find some leftover hydrogen from the big bang, new water will be difficult to come by 😉