Teri, Iβm so sorry you are dealing with this. We had something similar at my momsβs house.
We had just finished remodeling the downstairs bathroom so it was usable and DM didnβt have to go upstairs all the time. Unfortunately someone (and Iβm not going to say who) forgot to turn off the water to the upstairs toilet after using it and didnβt make sure the toilet tank stopped running. Weβll, it didnβt βseatβ and kept running. Which would have been OK (just a large water bill) except there was a clog at the street, so the (clean) water backed up through the new shower and flooded 3/4 of the downstairs. It was a shock when I went to check on the house (DM had not moved back in yet) and I stepped in more than an inch of water! π±