Upon placing down the Prismapump, water will flow in the direction the player is facing until it hits a block or reaches the limit of 159 blocks.[1] In the other direction, it will only flow as far as a regular water bucket.
As of the 0.18 update, the Prismapump is no longer placed as an actual block in the world, it simply acts like a better version of the Magical Water Bucket and goes back to your inventory after using it.
Sometimes the water may not flow long enough and you may have to use the Prismapump again. It is possible that it depends on your angle.
You can only use the Prismapump on a solid block, using it on water will not work.
Trivia[]
If the player has SkyBlock Addons installed, they have to disable the 'Avoid Placing Enchanted Items' function in order to place the block.
There is no purpose to buying more than one batch of these, as you can use the Prismapump as many times as needed.
Before the 0.18 update, the Prismapump would get placed as a block in the world and you had to place water on its side or top for it to activate. You could still break the Prismapump afterwards and reuse it elsewhere.
Anita. A set of 4 blocks costs one 
Bronze Medal and 
2x Jacob's Tickets.
Magical Water Bucket and goes back to your inventory after using it.
Added Prismapump.