Get your groans of ‘ew’ out now, because this is going to get gross. It’s a common problem in both new and old homes, in apartments and houses, in dorm rooms and mansions – water coming back up in the kitchen sink can happen to anyone. It’s disgusting when it does happen, and if it goes down (or rather, doesn’t go down) while you’re not home, it could overflow and cause water damage. No one wants to wake up in the morning to dirty sink water spilling onto the floor or stinking up the house, but unfortunately it’s probably the most common reason a plumber is called. But why does it happen? We’re here today to explain why water comes back up in your kitchen sink.