The water follows a parabolic curve. It is an example of projectile motion. I want you to calculate the initial velocity of the water. To do that, you need to calculate the constant horizontal speed and the initial vertical speed. Combine them by Pythagoras to get the overall initial velocity.
Hint: The initial vertical speed is the same as the final vertical speed with which it hits the surface of the water, assuming no air resistance. So do the second half of the projectile motion, from the top of the curve downwards to make it like the problems we normally do.
