: I recently discovered that every time I drain my kitchen sink when it has a lot of water in it, the water ands up bubbling up in the bathtub next to the kitchen! The water is filthy and foul-smelling. The water then drains away VERY slowly. Any ideas as to what this might be caused by, or how to fix it?: Thanks! : JohnJohn, You have a blockage in the line. Snake it out should solve the problem. It is not a pleasant job so you may want to call in a local plumber.