I had original plumbing (1922) in my house up until Covid lockdown when my dad and me started replacing it all. I had a leak in the upstairs toilet that my dad thought was a bad seal so i never used it. When I moved my bedroom to the main level I kept hearing running around in my attic and during the plumbing update we found the upstairs drain pipe was completely rusted away on the top side. So when I ripped the ceiling out of the main bathroom (just below upstairs) I was showered in rat shit for hours. Also I had to use a bandanna as a face mask because all the ones at the hardware store were out (this was the start of the pandemic when everyone was buying up everything)