Put the summary of the bug you're having here

What I expected to happen was...:
Glass Pane beneath the water holds off the water

What actually happened was...:
Water leaks in on corners and places itself into the glass Pane and spreads inside the building

Steps to Reproduce:
1. Dig a 4x4 hole into the ground 
2. Make a corner with  glass panes 
3. Place water on the outside of the corner