Undersink Plumbing Issues

[PlumbGate]

This looks like a great forum for my plumbing question! I am hoping someone can chime in with what my problem may be. House was built in 2000.

Issue:
I always have a smell in my dishwasher. No matter what detergent or how many times I run it when I open it up from a fresh wash, it stinks. I found that my dishwasher drain line has about 4 feet of slack in it so I just removed all of that and now it seems to drain much better. It does have a high loop. During this testing though, I found a few things. When I run the sink on the left with the garbage disposal, it seems to fill a bit and when I turn it on (the disposal), water rushes down the drain and shoots into the other drain geysering 3 feet up from the sink drain on the right. At that point the disposal side drains but looks like it is sucking the water lock out of the right drain allowing sewer gases to come up. I can from time to time smell sewer from here. I put a new tail piece on the right (today while fixing the extra dishwasher drain length) since the one on there was restricting flow. I got a larger one that allowed much more flow from the dishwasher. Looking down the drain with a flashlight while the dishwasher is draining shows a nice heavy stream of water. But when I took off the old tailpiece it stunk to high heaven like sewer. Not sure where this is coming from since I use this since many times a day the drains should be well flushed.

Some backstory - This setup never worked well. I replaced the dishwasher myself last year and instead of running it through the disposal tap (I got a new disposal with the dishwasher so I had the option of not using that setup by not punching out the dishwasher plug) I got a new right-side sink tailpiece with the dishwasher tap. I did this because when I removed the old dishwasher drainline, it was incredibly nasty with so much garbage in it right where it connected to the disposal that I didn't want to go this route again. I suspect it was like this because the disposal (as I found today) has never drained properly.

Any advice greatly appreciated! At this point I am ready to cap off the disposal and not use it anymore. I am on septic so they don't recommend using a disposal anyway.

Most of the undersink plumbing I have seen there is only 1 trap. Perhaps that it the issue?

VIDEOS
Right side draining - You can hear that "blub blub blub" when it is done for a long time.
Right Side

Left (disposal) side draining.
Left Side

Picture:

 

[TomFOhio]

Your drain is plugged up down the line someplace. Get it snaked out and then replace that elbow that both lines are going
into with a tee and then install an AAV (Air Admittance Valve) has high as possible under the sink on top of the tee.

 

[PlumbGate]

Thanks!

I don't think I have an issue with the line being properly vented. I'll try to clear the line with a snake and see if it clear the problem up. Since the right sink drains well, I would think if there was some sort of clog it would need to be in the left side plumbing somewhere right? I have removed all that before and did not see any clogs.

I really want to just re-plumb the entire thing to 1 trap. However, you can see from this mess that there is really no place to cut and put in new plumbing from what is visible. I am not sure how I would remove it all without having to cut into the floor and find clean plumbing to work with. Is that large "nut" on the main pipe threaded do you think?

 

[gagecalman]

Looks like a 2 in. x 1-1/2 in. flush bushing.
https://www.homedepot.com/p/2-in-x-1-1-2-in-PVC-DWV-Flush-Bushing-C48012FHD2112/100345144

Can you post a picture of the pipe below the 90° elbow where it comes thru the cabinet?
As Tom stated the elbow should be removed and replaced with a tee and an AAV. Right now it appears that you have a s-trap.
Jim

 

[Diehard]

Was that drain piping, as shown in your picture, installed by a licensed plumber?

 

[PlumbGate]

It looks like I do have enough room to cut this entire mess out and re-plumb.

 

[PlumbGate]

Was that drain piping, as shown in your picture, installed by a licensed plumber?

LOL! The house is part of a planned community and the builders around here stop at Home Depot on their way to the job site to pick up "plumbers" for the jobs. They get 1 house in 20 "inspected" by the county and that suffices for them all. It is not likely this mess was ever blessed by any governing body. I bought the house in 2010 but it was built in 2000. My home inspector did not flag it as a problem.

 

[gagecalman]

What part of MD?

 

[PlumbGate]

Damascus

 

[Diehard]

Yeah...the average home inspector wouldn't recognize the problem.

Don't forget you still need to add a vent when you re-pipe things.
As pointed out above.

 

[gagecalman]

I think I'd consider moving the copper lines to the back of the cabinet to get them out of the way. That's some crappy plumbing!

 

[will-b]

That's a very ghetto looking pipe job. Definitely not ideal placement or setup.

 

[gagecalman]

Good deal
https://www.amazon.com/gp/product/B0039OEMT4/?tag=skimlinks_replacement-20

 

[PlumbGate]

The cabinet is in a corner btw. So not against a wall perhaps that is why they did it this way?

 

[gagecalman]

Still needs a vent (AAV).

 

[frodo]

if it was mine. i would cut all of the drain crap out of there . and then i would install a 3'' coupling. then a 3x3x2 tee. with a 3x2 bushing in the top
in the bushing install a auto vent as high as you can install it
then. out of the 2'' on the tee. i would install a 2xx2 x 11/2 x 1 1/2 double wye in the end of the wye i would install a 2'' fitting x female thread adabtor
and a pvc screw plug
then, i would install a p trap on each sides of the wye to the sink and disposal

but thats just me



the water, cut that copper off 2'' above the floor and put those valves down where they belong

 

[PlumbGate]

if it was mine. i would cut all of the drain crap out of there . and then i would install a 3'' coupling. then a 3x3x2 tee. with a 3x2 bushing in the top
in the bushing install a auto vent as high as you can install it
then. out of the 2'' on the tee. i would install a 2xx2 x 11/2 x 1 1/2 double wye in the end of the wye i would install a 2'' fitting x female thread adabtor
and a pvc screw plug
then, i would install a p trap on each sides of the wye to the sink and disposal

but thats just me

View attachment 17758 View attachment 17759

the water, cut that copper off 2'' above the floor and put those valves down where they belong

Thanks for that. Are you saying all of my issues are related to a vent? I feel they are all related to the double p-trap. My house plumbing is properly vented but I know kitchen sinks can use more vent. I have been doing some research and most ranges from this (2 traps) is against code to "not a good idea" but haven't found anyone that actually recommends 2 traps. I'd think if I redid it I would remove the extra trap as I see no reason for it.

I do think I will cut it back as you suggested and go with all new plumbing. I am not against adding the vent under the sink but should I be concerned if I fill the sink up all the way and then pull the plug? Is there a chance it could back up into the vent?

I'd like to do pretty much as you suggest accept for 1 trap and instead of having the disposal drain go down as it exits to go straight across and link up with the main sink drain. Then move the dishwasher drain to the disposal tap. That is what I am seeing in most plumbing for 2 bowls, a disposal and a dishwasher.

 

[PlumbGate]

FYI: Since cutting all of the slack out of the dishwasher drain and also pouring around 20 gallons of boiling water down the sink drains my dishwasher is smelling much better. Not sure how long this will last but I am still planning on a total replumb of this sink.

 

[PlumbGate]

Also what is the purpose of the center of the double wye? Just a cleanout if needed?

 

[Mr_David]

Not really sure why Frodo suggested the double trap you only need 1. the double wye could be a single wye with a cleanout so you can snake it without taking drain apart.
best way to clean a a kitchen drain is with running water while you cable it.
Connect the dish washer drain to nipple on disposal and get rid of that branched tail piece.

The AAV won't leak unless it fails and you have a stoppage. It's like a check valve for letting air suck down into drain but when working to stop anything from coming out