One SLOW sink drain!

[PcrMusic]

Hello folks. I have run out of ideas, so I called in the pros, and they aren’t sure either.

I have a single slow draining sink (photo attached). The only one in the entire place of 4 sinks total. 2 toilets (no drainage issues) two bathtubs (no drainage issues).

Early on, I tried a drain bladder with the garden hose (running ~10 min) and when I turned the hose off, some water certainly came back at me (could hear water flow going down the drain though). Bought a cheapo snake from Harbor Freight that you can connect to a power drill and snaked the hell out of the thing 10 times over and nothing caught. I ran out of patience and re assembled a brand new p-trap to the sink. Using the sink for short 25-30 second spurts was okay and usually wouldn’t back up the drain, but anything more than that, I’d get standing water for a considerable amount of time (hour plus).

Threw some green gobbler, ZEP 10 minute drain, and other products down to little-no change in the water drainage. Before calling in “the pros” I bought Liquid Heat (I guess it’s sulfuric acid of some sort) as I was convinced the pipes were clogged/blocked somewhere. No change.

The pros were over and all they did was send a nicer looking more industrial snake down 5 times through (no debris- and actually now the water drains EVEN SLOWER for some reason).

Without doing anything else but send a snake down, the pro said he phoned his boss and told him the situation. His boss thinks there’s a problem with the ventilation in the house and want to jet water down the roof pipe to “flush out” any debris into the sewer line. I mentioned, if there was a problem with the ventilation, wouldn’t more drains in the home be having problems/backing up? They said, not necessarily because the drains are at different heights? On this floor particular, there’s a kitchen sink, toilet, bathtub, and bathroom sink (the problem sink). Is this dude just making BS up, or does that sound like it could legitimately be the problem? I wasn’t charged anything.

I also installed an air admittance valve (AAV) after the pros left, and it achieved absolutely nothing.

It’s been windy here, and I heard air in the pipe when I took the trap apart to install the AAV. I could feel the wind through the pipe opening in the wall, and the water in the toilet next to the sink (different drain line) was also swaying back and forth.

Is the pipe too horizontal in the wall? I have posted the best pic I have here. The kitchen sink drain is tapped into to the same drain line, but through the floor and further down in the basement. No issues there.

Suggestions welcome.

Thank you,

 

[Reach4]

I have a single slow draining sink (photo attached). The only one in the entire place of 4 sinks total. 2 toilets (no drainage issues) two bathtubs (no drainage issues).

Try shoving a soda straw from above so that it provides air to the drain maybe 4 inches down. Does drainage improve?

Is the slowness only when you have just a couple of inches of water in the sink, but not when you have 4 inches of water in the sink?

 

[Sponsor]

 

[PcrMusic]

Try shoving a soda straw from above so that it provides air to the drain maybe 4 inches down. Does drainage improve?

Is the slowness only when you have just a couple of inches of water in the sink, but not when you have 4 inches of water in the sink?

A straw down the drain, or down the overflow? I can tell you with hand washing it’s been the case that occasionally suds will come out of the overflow.

Also, the water will rise to the overflow if I let it. I’ve stopped messing with that method because [new info] if I let the water rise to “drain” through the overflow, then water starts leaking out of those three holes you can see pictured at the bottom of the sink. - I ask about the straw because I’ve stuck a straw down the overflow (no change) but not down the drain. Right now I have a bucket underneath the disassembled p-trap, and it catches all of the water- which I just dump into the bathtub when it gets too full.

 

[James Henry]

Did you check the grade on the drain pipe before you covered it up?

 

[PcrMusic]

Did you check the grade on the drain pipe before you covered it up?

NO! I honestly didn’t think it would be a problem. The toilet was a known problem as it had caution tape on it when we bought the home, but no indication that the sink had any problems. I do regret not thinking of it now that the walls are finished- but would the grade cause significant back flow when using the drain bladder? With the sink over flowed, and removing the p-trap, water drains from boiled both ways (from sink) and from drain.

 

[James Henry]

If that sink drain ties into a 3" stack I can't see you having a clog in the stack. If the sink has a pop up stopper, remove it and try it again.

 

[James Henry]

NO! I honestly didn’t think it would be a problem. The toilet was a known problem as it had caution tape on it when we bought the home, but no indication that the sink had any problems. I do regret not thinking of it now that the walls are finished- but would the grade cause significant back flow when using the drain bladder? With the sink over flowed, and removing the p-trap, water drains from both pipes (from sink) and from drain.

If it back grades towards the sink that would cause the slow drain.

 

[Terry]

If that sink drain ties into a 3" stack I can't see you having a clog in the stack. If the sink has a pop up stopper, remove it and try it again.

I would be looking at the stopper too.

 

[PcrMusic]

I would be looking at the stopper too.

Thanks James and Terry. Unfortunately the stopper and p-trap are both brand new. Assuming that it is the slope of the drain pipe, is there anything short of ripping the wall open to “fix” the slope, such as shortening the sink tail pipe to be above the wall opening?

 

[Reach4]

A straw down the drain, or down the overflow? I can tell you with hand washing it’s been the case that occasionally suds will come out of the overflow.

I meant drain. The fact that the suds came out of the overflow seems to negate the theory I was exploring, which was the overflow connection was somehow blocked. The overflow hole not only serve as an overflow, but also provide some venting below the stopper. Vessel sinks without overflows sometimes have slow drains.

Can you pull the stopper out, reconnect the trap, and see if the drainage is OK then?

One more test: with the drain pipe back in place, how much water can you pour from a bucket before the sink starts backing up?

 

[Terry]

What is below the floor there?
You have a long way to go in the wall if you were to change anything. And if you're getting air with the trap off, then it's not a venting problem.

 

[PcrMusic]

What is below the floor there?
You have a long way to go in the wall if you were to change anything. And if you're getting air with the trap off, then it's not a venting problem.

It’s exposed basement (and) close to the main sewer lines. Existing drain is in wall, in between the two closest copper water pipes. Are you thinking, drill through the floor and run a new drain line to the sewer line? Or something different?

 

[Terry]

It would have made more sense to bring the drain up from the basement for that sink.
I'm guess that you have 1-1/4" copper with a couple of bends, and it's super long before it hits a vent. Opening that all up again is a lot of work though.
We run 1.5" for sinks now, and 2" if we're doing kitchen sinks and double lavs.
1.25" was before I started plumbing. 60's and before.

 

[Reach4]

Not related to this problem, but that PVC in your picture has some problem I think. If it is a filter or softener drain, the problem is where/how it is going. If it is a gravity drain, then the lower bend should be a long sweep, and the one above be a medium or long.

 

[PcrMusic]

It would have made more sense to bring the drain up from the basement for that sink.
I'm guess that you have 1-1/4" copper with a couple of bends, and it's super long before it hits a vent. Opening that all up again is a lot of work though.
We run 1.5" for sinks now, and 2" if we're doing kitchen sinks and double lavs.
1.25" was before I started plumbing. 60's and before.

1.5, actually. But I agree it is quite long, but a newbie here didn’t know until now.

 

[PcrMusic]

Not related to this problem, but that PVC in your picture has some problem I think. If it is a filter or softener drain, the problem is where/how it is going. If it is a gravity drain, then the lower bend should be a long sweep, and the one above be a medium or long.

I’m curious now to know what you mean. I attached a better picture here now. The PVC is the kitchen sink. It comes into the basement up top with an “S” trap. Where it connects to the copper is where the problem sink should be draining from too.

 

[Terry]

The top bend can be a medium 90 and the lower one should be a long turn 90.
What you have on your kitchen drain are water fittings, not waste fittings.

Vertical to horizontal is a long turn 90. I see where you should be using two of those.
45 degrees is also considered vertical.

 

[James Henry]

If the sink has a pop up stopper, remove it and try it again.

 

[Reach4]

So maybe it is related. I would expect a clog to happen at about place B, where the long sweep should be.
However E should have been a combo( combination wye and 45). So maybe that would lead to a clog around there.

You do have a cleanout in that horizontal. Maybe you could rod to the right of that, but there are two elbows that might be hard to get through. It would be nice if you could rod from D and through C and on up. If you fix all of this, consider a bidirectional cleanout at D.

It's possible that your earlier rodding efforts from the bathroom ran the snake up into the vent system rather than down to C-D-E and beyond.

 

[Terry]

E would be better with a wye, not a tee.
B can be a combo with a cleanout on the end.