Pressure damage

Make extra sure that each tile is in fact granite. You can do that in the details tab after you click each tile.
I've noticed if you run out of the selected build material they just start using random other resources and build it anyway.

27 minutes ago, noldevin said:

I've noticed if you run out of the selected build material they just start using random other resources and build it anyway.

Which is something that should be changed, or at least given an option so it can be turned off.

I had a similar problem happen in my fresh water tank when some polluted water dripped into the lower left corner, except it was the two bottom tiles constantly taking damage. After dealing with the polluted water so it wouldn't drip into the tank anymore and having my dupes mop up  the small amount of polluted water that got into the tank, I noticed the damage was still happening. So, while they were making repairs I queued up building some extra tiles under that location. When the repairs and additional tiles were completed a large amount of polluted water suddenly appeared in that corner even though no more was dripping in from above. Since I was watching this area like a hawk during the repair and building of additional tiles I saw the polluted water gush in as if it has come out of the tiles that had been damaged. This leads me to think, maybe the tiles that were taking damage were also absorbing the polluted water that dripped in before I noticed.

Unfortunately I no longer have a save file from when this happened, but hopefully my description of what I saw will help the devs narrow down the cause of this bug.

Normal amount of 1 polluted water block is 800kg. As you can see in this screenshot there is 1155kg of polluted water. Seems like, Carbon Dioxide and small amount of clean water at bottom are blocking the spread of polluted water.

Anyway this is non realistic or seems like a bug