Just like the title, when water enters from the right side of the shower, the water disappears.
I did not know the detailed process because it was found late, but at first there was a liquid valve.
I tried to remove the valve, but the same problem occurred.
Upside is okay when I tested. I have not tried the other direction. (included save file)
I have not tried the same situation in a new game.
When I poured water from the right side of the shower two or three times in the attached save file, the water continued to disappear.
I hope you have a pleasant development.
Put water in the right side of the shower.