Found out the drain on our tankless water heater wasn’t installed properly. Apparently it’s acidic, and needs to be neutralized and through PVC pipes. Oh, and it should be flushed yearly. Whoops. I noticed it on Monday, not sure why I decided to look into the mechanical room, but yeah, we got some water damage that we now need to get taken care of as well. Used Rocket Plumbing again, awesome as always. Always fun to get these surprise household expenses.