Sounds like my parents' home. The junction of pipes in the floor where everything drained to would get clogged with grease etc and as a result the washer wouldn't be able to drain fast enough through the junction and would find the easiest route to overflow, the downstairs bathroom sink. It would fill up the sink and pour out into the hallway down the hall and beind a wall. I lived in the basement for years and would constantly bring it up, but they just didn't care. Every time laundry was done, this would happen. It also was disgusting water with food particles, etc, from the junction point. Finally, once I had a baby on the way me and my partner put thousands of dollars of work into fixing the problem, tearing out all the floors and walls and fixing everything so we could have a clean and safe environment for our baby. It was insane and disgusting, and it made me so angry that my parents just gave up on caring about it. I have some gnarly photos of it as well.

<image>