Water Phasing through stairs and slabs

It seems that water phases through stairs and slabs in the End. I tried to see if it was the same in the Overworld, but to no avail. Even destroying the water source doesn't stop the water flow. There also seems to be tiny chunks of water trapped between stairs. In one of the images, I "circled" the area where I cut off the water source. (I had limited supplies, so I did what I could to make it clear.)