Drainage Slow In Dual Sink

[PeteM]

I have this frustrating drainage problem with my kitchen sink. About a month ago when I put on the garbage disposal water came up in the other sink. Then I started to notice that the non disposal drain started to backup when using the faucet. Sometimes it didn't back up though - it was on and off thing. I went to Home Depot and the plumbing guy told me to check the trap under the non disposal drain and also the PVC crossover pipe. I did all that and it didn't show any blockage whatsoever. He then said you might have some grease in the line heading away from the sink. He gave me some heavy duty drain cleaner and said to leave it in overnight and flush it out with boiling water. I thought it helped a bit but when my wife pored some coffee down the rain and flushed it with water and it backed up again. I did a little research trying to figure this out and read about the proper routing of the dishwasher drain line to the disposal unit. Anyway, not sure what to do next. Im attaching a few pics. Hope you all can help. Thanks!

 

[Jeff Handy]

Your plumbing arrangement looks ok to me.
As long as the horizontal trap arm going into the wall is pitched slightly downhill, hard to tell from the pics.

Your dishwasher drain is ok as long as it goes as high as possible up to the top of the cabinet, on the way to the disposer inlet.
This is called a high loop, and there is likely also a high loop right on the side of the dishwasher itself.

Your drain line is definitely partly clogged, somewhere after it leaves the sink cabinet.

Does your wife pour coffee GROUNDS down the drain?

This is a drain killer, put those directly in the trash.

And don’t use the disposer as a magical garbage can.
Scrape all dirty plates and food waste into the garbage, then rinse the remaining bits off on the disposer side.
No bones, whole egg shells, banana skins, celery, stringy or fibrous stuff.
A few egg shell fragments are ok.

Pour any cooking grease into an empty can in the sink, set to cool in the fridge, then toss in trash.

Meanwhile, try drain cleaner again, use half a gallon of Instant Power, let sit for half hour to an hour, do not pour it into disposer side.

Rinse with lots of very hot tap water, boiling water is dangerous to carry around.
If you use boiling water, pour it into a colander to avoid splashing.

If sink is still backing up, call a plumber.
Tell him you used drain cleaner so he will be careful not to get burned while snaking.

 

[PeteM]

Jeff,
Your remarks were really helpful. I checked the horizontal trap arm going into the wall and its slightly pitched back towards the trap. That can't be good-its always been like that.
Its almost like I would need to raise that trap up to the bottom of the sink in order to create a better flow outward. Not sure how I would do that? Im sure there is a partial clog due to years of grease buildup and that backward slop of the trap arm doesn't help things. Thanks again!
-Peter

 

[Jeff Handy]

The P trap looks like it can slide up about an inch higher, until it bumps into the bottom of the Tee above it.

If the lower outlet of the Tee is bottoming out into that fatter top part of the P trap, you can neatly saw off some of the Tee bottom leg.

So the whole P trap and trap arm can slide up to a higher pitch.

Loosen the nut on the trap adapter while doing this, then re-tighten later.

You still need to clean the drain line with Instant Power, another drain cleaner, or buy a 25 ft snake, or hire a plumber.

The clog could be close, or 5, 10, or 30 feet or more away.

You can also cut the drain line if you have access from a basement or crawl space, then install a clean out and snake from there, to reach farther clogs.

Install the clean out so the plug opening is well above the height of top of drain pipe, to minimize water running out of it.
But not so vertical that you can’t get a snake into it, if access is tight.

 

[Jeff Handy]

3/8 in. x 25 ft. Drain Auger

https://www.homedepot.com/p/306536219


This is a good cheap drain snake for kitchen drains.

It will make some slight oily metal marks on carpets or other surfaces, so put down some Harbor Freight cheap plastic tarps.

After the first use, it will get dirtier for next time, so tarps will be useful in the future.

 

[PeteM]

Thanks so much Jeff. I'll give it a try this weekend.

 

[SHEPLMBR]

The t should really come off of the garbage disposer. In my opinion, it is piped backwards. Others may tell you different.

 

[TomFOhio]

That's a disposal kit that is on there. Its correct.

 

[PeteM]

Finally got everything draining good now. It was just many years of grease build up in the pipe heading outside. Used three bottles of InstantPower drain cleaner over the course of a week.....It does work!

 

[Jeff Handy]

Did you ever raise that trap higher up?

If not, it will be likely to clog again more easily.

Meanwhile, congrats, hurray for Instant Power!

 

[PeteM]

No I didn’t Jeff. Just being lazy. The guys at HomeDepot really push this Instant Power stuff. I guess it’s better than all the other stuff they sell.

 

[Jeff Handy]

It does often work, when used properly and safely.

 

[PeteM]

Yeah I had my Corona Virus Hazmat outfit on when pouring down the drain. Thanks again for all your help!

 

[Jeff Handy]

Don’t smoke, I think a byproduct of drain cleaner reacting with grease can be hydrogen gas.