[flav77 (OP)]

For an experiment I wanted to know if it was possible to dismantle the water molecules with no other external input than a stream of water. Thank you for your answer.

[Kryptid]

In principle, you could. Shoot two streams of water at each other and the collision should generate at least some heat. If you could fire the streams at each other fast enough, sufficient heat should be liberated to break down the water molecules. Of course, whatever method you are using to get the water up to such a speed might break them down as well.