Our laundry room is in the basement, directly below the kitchen. Under the laundry tub is a floor drain. When I drain the dishwater from the kitchen sink I have noticed that soapy water comes up from the floor drain downstairs. It usually leaves a puddle of suds maybe 2-3 feet wide. Is this a pipe issue or a vent issue or a floor drain issue? There never seems to be a problem when the washing machine empties into the laundry tub or when the kitchen faucet is on and running just clean water down the drain, only when the sink drains after washing dishes. Any suggestions?