Hello,

I recently replaced a double bowl stainless sink in the kitchen, with the same type. I replaced the drain on the one side, and replaced the other side with a garbage disposer. The sink is now backing up into both bowls when the dishwasher empties and when the disposer is used. I had the plumber out 2x and the line was snaked 30 feet and almost 100 feet (into the main line into the street). There is no blockage. Plumber mentioned building a vent may solve the problem. Before I spend the money, I want to be sure that this is a good next step, and if you have any other suggestions. Please help.

Thank you.

You mention snaking the drain line and 100 feet into the main. Did he remove the trap and snake the line from there? If the sink's unvented then that could impede the passage of all the garbage that you're putting in your system. Also if you have a older home with 1 1/2" drain lines you may be overloading the system with the disposal. At the very least I would add a AAV,( Air Admittance Vent) cheater vent just after the trap. Good luck, Tom

Hello,

I recently replaced a double bowl stainless sink in the kitchen, with the same type. I replaced the drain on the one side, and replaced the other side with a garbage disposer. The sink is now backing up into both bowls when the dishwasher empties and when the disposer is used. I had the plumber out 2x and the line was snaked 30 feet and almost 100 feet (into the main line into the street). There is no blockage. Plumber mentioned building a vent may solve the problem. Before I spend the money, I want to be sure that this is a good next step, and if you have any other suggestions. Please help.

Thank you.
Thank you for your quick response. One question... can I put a vent on the trap under the sink... on plastic pipes... or do I have to redo the PVC pipes and put a vent there? The AAV you are speaking of... where exactly do I put this?

One question... can I put a vent on the trap under the sink?
Yes you can,(see image). You cut in a tee and install it behind the trap.
Good luck, Tom

Thanks!