You have to be careful with water, otherwise the oxygen will absorb one of the hydrogens, becoming fluorine, and dissociate from the other, and if this happens enough, your water turns into hydrofluoric acid.
(Okay, just so we can be clear, as if the misinfo CW wasn't enough, no, this obviously doesn't happen. The only way to make oxygen into fluorine is nuclear fusion, which doesn't just spontaneously happen.)