So vitmori is thinking to small for sure. The very first thing I would do when trying to visualize a jet of water? Ocean. Deep deep ocean. The water pressure that would exist so deep would basically come out like a friggin lazer. Saw this done in a D&D game once. The player had a scroll of teleportation. Long story short they created a friggin portal at the bottom of the ocean and opened it up infront of a Dragon. Basically cutting the thing in half.
