Using a water bucket and clicking too fast makes a glitch. 

When you use a water bucket and click too fast (7-10CPS or above) it might glitch so there's both floating water and water in your bucket, the opposite, or the water is gone from your bucket but isn't moving on the ground.

If you try to use the empty bucket, it refreshes and works again.

(Other people can't see it, but if you jump in it they see you floating.)