First of all, I am currently unaware if anybody else has had the same idea as me but I think "Hose-pipes" should be added to Terraria, this would probably have to be unoffically added as Terraria is now no longer being developed.
A Hose-pipe should have 0 damage, average knockback, average speed and uses 8 mana. For each 8 mana consumed the Hose-pipe should shoot 1 block of water. This should also be a hardmode items maybe found in chests.
There could also be a lava version called something original like the Lava-pipe. 0 damage, weak knockback, slow speed, uses 16 mana per block of lava.
Edit: what I ment by the "Lava-pipe" doing 0 damage is that the weapon itself does not do any damage but the lava does.