Slow-draining Kitchen Sink But No Clogs

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mj987

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Hi! New member and I have a question.

Our kitchen double sink has been very slow draining for more than month. Used to be fine.

On either side of the sink, if you put water it will fill up the sink, and come up on the other side too. Eventually it will drain.

All our other drains are fine.

We’ve tried:

-plunger
-cleaning the p-trap
-snaking all the way to main pipe

Not quite sure how to include photos so I am attaching them.

First is a photo on the pipes under the sink.

The second photo shows what may or may not be an issue? - the pipe from the p-trap leading to the basement actually slopes up a bit (I am holding a ruler to show the slope).

(Also, some recent history in case it’s relevant: I mentioned the slow drain issue starting up at least a month ago. Also 2 weeks ago our very old dishwasher started leaking into the floor right into the basement. We’ve replaced the dishwasher. It’s probably not related to the slow-draining issue at all, but I just wanted to mention it.)

Is the set-up under the sink correct or is there something wrong with it causing the slow-drain?

How do we fix this?

mj

Thanks!
 

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Reach4

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Not right. Big problem, but it does not explain a slow drain.

The problem is that you don't have a vent. What you need is sanitary tee atop the pipe going through the floor. The top of that goes up to an AAV. The side port gets a trap adapter, and that connects to to the P-trap.

During that work, make sure that the trap arm of the P-trap will have the proper slope.

That tee that you have has a down pipe that can be cut. The P-trap connects to that, and that connection has some adjustment. Cut the thin plastic tee down pipe so that its bottom is nearer midway into that expanded part of the P-trap by the nut. That way you can adjust up or down.

You could do that cutting now, but it would still not give you the vent needed to keep the P-trap from siphoning dry. The symptom you could have from no vent is a smell.

Slow drain-wise, somebody may have a better configuration for you.

I don't see your ruler.
 

Stuff

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More likely the problem is a restricted drain. You probably snaked it with a small cable with a tiny end which doesn't fully open up the drain. Best to call in a pro with the proper equipment. Otherwise try an enzymatic cleaner like Bio-Clean.
 

Jadnashua

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Is that T between your sinks one with a baffle in it? If not, when the one sink with the disposal on it runs, it will pump waste past the T and potentially into the other sink. Other than that, you have an S-trap, and probably the easiest way to resolve that is with an AAV as described, but then, those are not allowed everywhere...you'd need to know if your local codes allow them. If not, it gets a lot more complicated.

It's nicer if the pipe is larger once it passes the trap to handle the volume. Your slow draining is a symptom of a partial clog somewhere. Not all snakes are created equal. How big was the head on the one you used?
 

Jadnashua

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What HJ is alluding to is that the lack of a proper vent tends to do two things: allows the waste to drain too fast, and siphon its own trap, and allows other waste in the line from pulling water from your trap. IOW, a lack of a proper vent normally does not slow things down under most circumstances.
 

Queen50

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Hi! New member and I have a question.

Our kitchen double sink has been very slow draining for more than month. Used to be fine.

On either side of the sink, if you put water it will fill up the sink, and come up on the other side too. Eventually it will drain.

All our other drains are fine.

We’ve tried:

-plunger
-cleaning the p-trap
-snaking all the way to main pipe

Not quite sure how to include photos so I am attaching them.

First is a photo on the pipes under the sink.

The second photo shows what may or may not be an issue? - the pipe from the p-trap leading to the basement actually slopes up a bit (I am holding a ruler to show the slope).

(Also, some recent history in case it’s relevant: I mentioned the slow drain issue starting up at least a month ago. Also 2 weeks ago our very old dishwasher started leaking into the floor right into the basement. We’ve replaced the dishwasher. It’s probably not related to the slow-draining issue at all, but I just wanted to mention it.)

Is the set-up under the sink correct or is there something wrong with it causing the slow-drain?

How do we fix this?

mj

Thanks!

OK I'm not an expert, but when our double sink acted like this, we unscrewed the P-trap where it goes into the wall and found a clog of grease that had accumulated over time. It plugged about 40% of the pipe!
 

Reach4

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I think the more likely place for the clog is under the floor where the drain turns from vertical to horizontal.
 

mj987

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Thanks for the suggestions.
We used this 1/4" hand auger
https://www.lowes.com/pd/Cobra-1-4-in-x-20-ft-Music-Wire-Drain-Auger/999956882

There are plumbing vent stacks on the roof, so I know the system is vented. Haven't checked if those are obstructed, but the fact that it's just one drain that's slow makes us think it's probably not that. (2-story house, going up on the roof is kind of intimidating).

I guess we could try an enzyme degreaser. Bio-Clean is online only and kind of pricey - are any of the brands at Home Depot or Lowes worth trying or should I just order for Bio-Clean? (other brands: Zep, Instant Power, etc)

Thanks again.
 
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SteveW

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Bio-Clean seems noticeably different from the products I've tried at the big-box stores. Yes, it's pricey, but lasts quite a while and really does work if you follow the directions. You'll need to use it nightly for a week or so. The beneficial bacteria in it actually get into the gunk on the pipes and reproduce, and it takes a little while.

Other issue to look at is your disposer. If more than 5 years old, might be time to replace, preferably with a better unit such as an Insinkerator Evolution. I used to get a lot of clogs (from carrot and potato peels especially) with my old disposer, but once I invested in a high-end Insinkerator, problem solved.
 
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