Elementalist water sorcerers get produce water instead of the produce flame cantrip. Is this water drinkable and how much is produced per casting? Since it does persistent damage on a critical I assume the water keeps bludgeoning the target so the water must stay around at least for a while.
The spell does only what it says it does and nothing more... which is to say it does damage.
Any other applications of the spell are firmly ask your GM territory and outside the purview of rules discussion.
It leaves as much water as a ray of frost leaves ice, how many vines are left after a Tanglefoot, ect...
The spell seems like it would just act like a waterbomb that must be thrown at someone as soon as it exists (as that is what the spell describes happening). It is pretty difficult to make much use of water than has splashed on someone and soaked into their clothes, especially if it is only one waterbomb's worth, and may not even persist at all once it is done doing bludgeoning damage(the water might just vanish back to the plane of water or wherever it comes from after it does it's damage)