Problem with dual sink water backing up due to disposal

[Carloscbj89]

Hi, so I have a dual kitchen sink and both drains are connected to a single drain pipe. The problem I'm having is that when I use my garbage disposal water ends up backing up on the other sink and of course it brings up residue and smelly water.
I have a 1/3 HP garbage disposal that has the dishwasher drain attached to it. When the dishwasher drains into the garbage disposal, water doesn't back into the other sink.
I don't believe the drain pipe is clogged, although it's possible. But I think the problem I have seems more of an improper installation. I'm attaching a picture to this post of my current setup. I'm hoping that someone could provide some recommendations as to what I should do to solve this problem. I've put up with this for three years and I'm done ignoring this problem, so any help is truly appreciated.

 

[Reach4]

You have two traps, which is wrong, but that is not causing this symptom.

If you run the faucet up top at full blast for 10 minutes into the not-running disposal, do you get any backup into the other bowl?

 

[Sponsor]

 

[Carloscbj89]

You have two traps, which is wrong, but that is not causing this symptom.

If you run the faucet up top at full blast for 10 minutes into the not-running disposal, do you get any backup into the other bowl?

So I just run a test where I filled up the sink that doesn't have the garbage disposal and when I let it drain the water I saw some of the water start to back up in the garbage disposal sink but only half way it didn't backed up all the way into the sink. So could that mean that I do have a partial clogged drain pipe? And if so, what can I do to fix that? Thank you!

 

[Reach4]

So I just run a test where I filled up the sink that doesn't have the garbage disposal and when I let it drain the water I saw some of the water start to back up in the garbage disposal sink but only half way it didn't backed up all the way into the sink. So could that mean that I do have a partial clogged drain pipe?

Yes.

And if so, what can I do to fix that?

Does the output of the trap go through the cabinet to the left via a tan pipe? Or does it go right into the wall, and the thing that looks like a tan pipe is something else.

You have something with a white cap high behind the disposal. Could that be a cleanout?

 

[WorthFlorida]

Did this always have the problem or did it just start?

Remove the trap from the sink and that will eliminate one problem as long as there is no blockage past the second p trap. But it seems there is some blockage past the second p trap since water should not back up to the right sink from the disposal sink. Another source could be the vent is too far from the sinks causing a slow drain. The way that drain pipe comes from th eside is usually conductive of a remodel at one point.

The sinks are 1 1/2", the drain line must be a 2" pipe? Can't quite tell from the pictures.

 

[Carloscbj89]

Yes.

Does the output of the trap go through the cabinet to the left via a tan pipe? Or does it go right into the wall, and the thing that looks like a tan pipe is something else.

Yes, the tan pipe that goes thru the cabinet is the drain pipe that's connected to everything else.

You have something with a white cap high behind the disposal. Could that be a cleanout?

So when the kitchen was renovated to my understanding each sink was connected to an individual drain pipe. The contractor said that due to the new kitchen sink there was no space available to connect one of the sinks to the pipe that had the white cap, so they connected both sink drains to one drain pipe such is the tan pipe in the picture.

 

[Carloscbj89]

Did this always have the problem or did it just start?

Remove the trap from the sink and that will eliminate one problem as long as there is no blockage past the second p trap. But it seems there is some blockage past the second p trap since water should not back up to the right sink from the disposal sink. Another source could be the vent is too far from the sinks causing a slow drain. The way that drain pipe comes from th eside is usually conductive of a remodel at one point.

The sinks are 1 1/2", the drain line must be a 2" pipe? Can't quite tell from the pictures.

View attachment 54803

So the problem started after the kitchen was renovated. Apparently each sink drain had its own drain pipe. I'm the picture you'll notice that a pipe has a white cap close to the garbage disposal. Because there was no space available they connected both sink drains to one drain pipe which is the tan pipe that is 2in diameter that goes into the cabinet. The sink drain pipes are 1 1/2in pipes.
The reason the is a second trap in the non disposal drain was because it smelled all the time. Initially the non disposal drain connected directly to the disposal as you have in the picture you posted. But there was a smell all the time coming out of the non drain pipe and water would back out even more. So the trap was added and it helped with the smell and slightly with the water backing out.
As far as a vent pipe, I'm not sure I understand what that it and how I could tell if the is one or where it would be.

 

[Reach4]

As far as a vent pipe, I'm not sure I understand what that it and how I could tell if the is one or where it would be.

1. Show us a picture of the tan pipe as it continues, including until where it turns down.
2. Is there a basement under there?
3. What is the slope on the tan pipe? Use a level.

You will probably be removing the left trap and rodding thru there into the tan, but we would like to see where the drainage turns down.

 

[MACPLUMB]

You need to call a Professional PLUMBER !
Or rent a Electric Power Snake at Home Depot and do it YOURSELF !

 

[WorthFlorida]

...As far as a vent pipe, I'm not sure I understand what that it and how I could tell if the is one or where it would be.

It all looks like the root cause is at the other end of the horizontal run.

The trap may not be more than 6 or 8 feet from the vent stack but the slope could be part of your problem. There should not have been any odors with the first set up and it could be the trap is too high from the main waste sanitary tee. A lack of venting could also cause slow draining and the trap was getting sucked dry causing the odors. If the horizontal run is in its limits and the slope is good, adding an AAV after the trap may help as long as you know the drain has no blockage. If the horizontal run is too long and not sloped correctly, food waste from the disposal may be clogging up the works.

Another configuration is possible. Place the p trap after the right sink and tee into the tailpiece for the disposal. https://terrylove.com/forums/index.php?threads/garbage-disposal-plumbing-done-wrong.59911/

Google "p trap design"