Double Kitchen Sink with Disposal Drain Help w/ Video

[floatsonwater]

I have a double kitchen sink with disposal and while the water is running it's backing up slightly through the other drain. When you run the disposal some water splashed out of the sink and the backup on non-disposal side gets higher until you shut disposal off. I attached a youtube video link as it's much easier to watch than describe.

The trap and everything is clean as a whistle under the sink, I took it all apart. I also removed the disposal and ran water through it from anther sink and it's draining fine. I also tried some liquid drain cleaner but that did nothing. So does the main line need snaked? Maybe it's a venting issue?

YouTube Video:

 

[wwhitney]

I don't know if your problems are due to venting, but you do have a venting problem, namely your sink does not have a proper vent.

Michigan uses the IPC, so if the the vertical pipe coming out of the floor is 2", and if you had no garbage disposal, the arrangement shown could be a qualifying Combination Waste and Vent (confirming that would require knowing what is happening below the floor with the drains). But IPC 915.1 on combination waste and vent prohibits garbage disposals on combination waste and vent, so your arrangement doesn't comply with that. Also, I'm not sure if that vertical pipe is 2" or 1.5"; if it's 1.5", it's too small anyway for combination waste and vent.

The solution to your vent problem would be to replace that street quarter bend going into the top of the san-tee with a (street if desired) san-tee, and then adding an AAV on the top entry of the new san-tee (at least 4" above the trap arm, which is the pipe going to the side entry of the existing san-tee.

As to whether that would help with your problems, I don't know. But if you want to find out, you could temporarily remove that cleanout plug and see if your symptoms change. If they improve, adding the AAV would probably help (if there some sort of clog or other problem where removing the cleanout plug causes air to be expelled out of that opening, the AAV won't help).

Cheers, Wayne

 

[Sponsor]

 

[floatsonwater]

Thanks for the tip. I will remove the cleanup plug as a test. The vertical pipe coming out of the floor is 2". Not sure what happens below it, this is a second floor condo.

 

[Reach4]

The problem is not venting. If you remove that plug, expect flooding under the sink.

Does your tee have a baffle to help direct the water from the disposal downward? It probably does, but if you don't remember, it would be good to check.

 

[floatsonwater]

The problem is not venting. If you remove that plug, expect flooding under the sink.

Does your tee have a baffle to help direct the water from the disposal downward? It probably does, but if you don't remember, it would be good to check.

Yes the tee does have a baffle

 

[wwhitney]

If you remove that plug, expect flooding under the sink.

Good point, if the problem is caused by a clog downstream of the cabinet, that would be likely. Better just to crack the plug and see if water slowly dribbles out (after possibly a little air, as the elbow above the san-tee is likely air locked). Or just start with snaking the drain via that cleanout plug, and only consider venting as a cause of the problems if that is unproductive. [Venting is still a problem regardless.]

If there were an obstruction in the tubular tee or between that tee and the san-tee, that would explain the symptoms without causing any hydraulic pressure at the cleanout plug, but that possibility seems to be ruled out by the OP's statement that "The trap and everything is clean as a whistle under the sink, I took it all apart."

Cheers, Wayne

 

[Reach4]

Or just start with snaking the drain via that cleanout plug, and only consider venting as a cause of the problems if that is unproductive. [Venting is still a problem regardless.]

Yep. Venting is not right-- but the other bowl filling is not caused by the bad venting. The new AAV OP need to add to meet code is to keep the trap from siphoning empty.

 

[floatsonwater]

I will rent a snake from Home Depot and add the AAV. Hopefully that should do the trick. I think that’s the message here.

 

[floatsonwater]

I wanted to give an update. Opening the clean out port seemed to fix the problem and when putting the cap back on the problem came back so I installed the AAV and everything seems to be happy at the moment.

 

[Reach4]

I am surprised, but I am glad that fixed it.