Slow draining kitchen

Please help me figure out why the sink will not drain at an acceptable pace. It will drain fine when just running the water but if you fill up the sink and let the plug out it will not drain fast and towards the end just stop leaving standing water. Also, when the dishwasher empties it backs up into the sink.

Any advice is much appreciated!

 

I'm assuming that it used to work OK but now doesn't.....

1st step would be to make sure the trap isn't partially plugged up. The trap is the U or J shaped pipe next to the disposal. You can remove it by unscrewing the two big white plastic nuts. Have a tray or something under it as some water will spill out. If you're lucky you will find it partially clogged with gunk that you can clean out.

If that doesn't solve the problem, you can try pouring a pan or two of boiling water down the drain in case grease/fat from cooking has partially clogged the drain pipes.

If that doesn't do the trick, then it's probably time to use a plumbers snake to snake out the drain line.

 

It sounds like the drain/trap piping may be partially clogged with grease build up. I had the same problem last year and when I removed the horizontal drain line I found that it was 3/4 blocked with gunk.

I used a bright flashlight to shine through the pipe from behind and the clog was very obvious.

 

In addition to the comments above, that is not an approved location for an AAV. It should be as high as possible, meaning it should be run behind the sink up against the bottom of the countertop.

It would be better if it was in the wall behind the cabinets, so that the top of it could be 6" above the flood line of the sink. They sell boxes with grilles to allow it to remain accessible.

My guess is that it's probably plugged.. And you could have a slow drain to boot. I'd remove the AAV by unscrewing it... put a pail under there to catch any spills and then drain the sink. If it drains fast, you know the AAV is the problem. So as long as you are doing it put it up as high as you can.

 

The sink hasn't drained right since I bought the house. I switched out the double basin sink last year with a single basin and a new disposal. I feel like the height and angles of the trap/pipes are ok. I had checked for clogs and also snaked the line with no issues there.
I thought it could be the AAV but don't know much about it or if they can clog or go bad. I will take your advice and unscrew it and see how the sink drains and then try and raise it somehow.
Thanks everyone!

 

If you remove the AAV and it drains faster. it still might be a clog!

I ran into the issue on two separate slow draining sinks in a house with new AAVs installed. Replaced the AAVs, tried this, tried that. Couldn't figure out why it was draining better with the AAV removed. Turns out... a good snaking solved both issues.

So that's my vote. Years of grease and buildup is likely caught up at an elbow below all this and needs a good snaking.

 

The fix that didn't fix it.
So I replaced the AAV (it was gross from back up) and raised it up but still a slow flow and practically a no flow when you let out a sink of water. I lit up the horizontal part and the P-trap and seems like there is an air imbalance still. As soon as you unscrew the AAV it flows wonderfully though.
Would it benefit me at all if I put a vent off the horizontal part?

 

Well that's not exactly as high as possible. It should not be below the bowl of the sink, which it still is.

Did you snake the drain while you had it off? Have you dumped out the trap and ensured it's clean?

 

I got it as high as I could. It was difficult to even get my hand up to screw it in where I did.
I did not snake the drain again when I had it off. I did take a camera shot and was able to see all the way down to the basement when it hits an elbow. I did snake the drain down from the access point in the basement and it was clear but I will try that again. maybe get a more powerful snake, maybe I need to go further.
like I said, this drain has had this slow flow problem since we bought the house. before even a disposal was added.
Thanks for your feedback.

 

To get it higher, (but still under the countertop) you would assemble a section of pipe and a couple 45 elbows with the AAV on top, and stick it in up the back left corner behind the sink. (The top of the AAV would be right under the countertop) Then glue the bottom of that entire assembly into your sanitary tee.

More than that, your problem is the slow running drain, so the problem is likely below the cabinets. More snaking or professional jetting might be needed. Or your plumbing is improper, but no way to know that without being able to see everything between the sink and stack.

In a house I bought, the slow running sink problem turned out to be a sagging pipe that was also running uphill. So you never know.

 

I read about rubber banding a rubber glove to the where the AAV attaches to see if it sucks in or blows up when draining water and mine blew up. So, that leads me to believe there is a blockage of some sort way below. On to that snaking......

 

Please move your AAV also. Think about it... the whole reason your AAV was full of crap was because it's below the water level of the sink. It can't suck air if water is being forced up the AAV by water pressure.