Okay, double sink, left side food disposal, right side normal drain. Both drain pipes have their own traps and then "Y" together before going into the wall and down into the basement. The dishwasher also drains into a 20" drop pipe to a trap and then into the wall about 6" below the sink drain. Today the sink drains backed up while disposing of some food in the sink.

Noticed under the sink that some of that food backed up through the dishwasher drain and sprayed out of the top of the pipe under the sink. What puzzles me is that I apparently have a 1 1/2 "drain" pipe going through the floor about 2' away from the sink drain. I can only see it coming through the basement ceiling since it is in the wall space. This pipe is obviously the source of my wet ceiling in the basement, but there is no food. Why is it there and how does this work? Should there be a cap on it?

This also happened about a month ago but I was able to get it to drain without taking anything apart. This time, not as fortunate, so I took off the sink traps to drain the sink out and try to use a snake into the wall to look for a blockage. Nothing found so far. Next step is the dishwasher trap to see what I can find.

My last resort will be to cut an elbow out of the pipe in the basement where is starts a horizontal run so that I can snake the pipe in two direction from there. If anyone knows anything about this mystery drain in the floor, like a backflow valve problem or something, I'd really appreciate it.

Tom G.

Description a bit complex. Show us a picture of piping under sink.

Bought a 25' plumbers snake today and was able to free enough of the clog for the sinks to drain again. I felt some resistance about 10' to 15' feet into the pipe, so I think I might have a slight low spot along the horizontal run in the basement. I also bought an 1 1/2" rubber PVC cap with a screw clamp to stop any future backflow out of that other pipe that spills into the basement about 2' away from the sink drain. Then I ran the dishwasher with some bleach to force some more hot water down the drain to help clear it some more.

Where did you snake from? Back to you, Tom

Where did you snake from? Back to you, Tom

Snaked from the removed trap under the right-side sink.

Then all you've snaked is the horizontal line in the wall. If you still have a probl34em then get a longer snake and snake from the kitchen roof vent. Put out enough snake to reacthe base and 16 more feet. Good luck, Tom

Then all you've snaked is the horizontal line in the wall. If you still have a probl34em then get a longer snake and snake from the kitchen roof vent. Put out enough snake to reacthe base and 16 more feet. Good luck, Tom

I also snaked up this 1 1/2" PVC pipe that comes through the ceiling in the basement about 2' to the side of the subject sink drain. Water definitely came out of this during the clog. Does this connect into the 2" sink drain pipe behind the wall? Should it be capped off?. because that's what I did.

You snaked up when you should be snaking down. Go back and try again. Good luck, Tom