are you sure it isn't the windows and the rain? me and doughboy also could have misplaced a wall
I'll come on and fix
I kind of suspect it is the windows, but I'm not sure.
The water blocks that fall down don't come from the windows (although this time they didn't appear at all).
Also, last time it only filled up the bottom room, and not the rooms above it at all, which is weird, because if it is the window, then the windows are only in the upper rooms.
And it happened last time when I built it, and I went over it again and again to check I had put in all the background walls.
Just seems to be a weird glitch with that particular building on that spot on that planet.
But Doughboy was nice enough to place a few drains in there for me, so it's all good now. Thanks!