After all that effort, his washing machine waste is now sharing a single waste trap with his sink. That means that when his washing machine waste starts to get

After all that effort, his washing machine waste is now sharing a single waste trap with his sink. That means that when his washing machine waste starts to get stale and smelly (they can get surprisingly bad) that gas will come straight back out of the sink plug hole. Source: I have the same setup in my house and it sucks (and I'm not practical or motivated enough to fix it).