Issue with sewer smell and p-trap

Users who are viewing this thread

Mike Boston

New Member
Messages
3
Reaction score
0
Points
1
Location
Boston
Hi All, I need your advice.
We live in a high rise 13 floors building (1969) and our top floor apartment has 2 floors ( 12 and 13). Our top floor bathroom sinks constantly losing a water seal and passing sewer gases inside our apartment. It's very random and a lot of times its associated with heavy rain but today we had none with only thing different outside temp dropped below zero last night, sometimes we have this issue within 6-12 hrs from last use of this sink, sometimes within a few days/week).

I'm posting my pictures with measurements for you to spot any potential issues with this p-trap itself. As a side note, we do have another sink inside our 1/2 bathroom same top floor (across the wall)connected to the same vent stack just a little bit lower entry point into the main vent stack with no issues.
We already installed roof main vent stack back drafting Air Admittance Valve to eliminate high wind pressure from the roof back to the vent stack.
Similar to this one - https://www.zoro.com/studor-air-admittance-valve-pipe-1-12-to-2-in-20301/i/G2340764/

Thank you for your help,
Mike/Boston

IMG_1113.jpg
IMG_1114.jpg
IMG_1111.jpg
 

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,412
Points
113
Location
IL
We live in a high rise 13 floors building (1969) and our top floor apartment has 2 floors ( 12 and 13). Our top floor bathroom sinks constantly losing a water seal and passing sewer gases inside our apartment. It's very random and a lot of times its associated with heavy rain but today we had none with only thing different outside temp dropped below zero last night, sometimes we have this issue within 6-12 hrs from last use of this sink, sometimes within a few days/week).
I am not a plumber. One solution would be to replace the low trap with a high trap with its own AAV. So you would replace the P-trap at the bottom with an elbow. That elbow would receive the output of the new p-trap at an angle.

I am not sure how to best implement that while making the result almost as pretty as your existing installation. The trap arm length needs to be 2 pipe diameters minimum.
 

Mike Boston

New Member
Messages
3
Reaction score
0
Points
1
Location
Boston
I am not a plumber. One solution would be to replace the low trap with a high trap with its own AAV. So you would replace the P-trap at the bottom with an elbow. That elbow would receive the output of the new p-trap at an angle.

I am not sure how to best implement that while making the result almost as pretty as your existing installation. The trap arm length needs to be 2 pipe diameters minimum.

do you think my issue with a minimum distance from p-trap to the vent pipe? Looks like I have a 1 1/2 inch pipe and my wall covered with 1/2 inch durock and 3/8inch tile on top of Schluter mortar 2/8 and waterproofing membranes, based on my picture I see around 2 inch outside the wall and this drain pipe crossing 2x4 wood reinforcement?

IMG_1116.jpg
IMG_1115.jpg
1623s.jpg
IMG_1111 (1).jpg
IMG_1114 (1).jpg
 
Last edited:

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,412
Points
113
Location
IL
do you think my issue with a minimum distance from p-trap to the vent pipe?
No. I suspect the problem is that the tailpiece is so long, that the water goes fast, and the momentum carries the water right through the trap. Now I would not have predicted this, but you have a symptom compatible with that theory.

I brought up the minimum for the new under-lavatory trap proposed.
img_2.jpg



Of course the other option is to open the wall and put a new santee higher.

A temporary workaround is after sending a bunch of water down the drain, you follow that up with a slow trickle of water to refill the trap. Maybe do that for a while to confirm if trap-emptying is the problem. So maybe run a trickle from the faucet, or put a little water in the bowl and leave only the smallest crack around the stopper.
 
Last edited:

Mike Boston

New Member
Messages
3
Reaction score
0
Points
1
Location
Boston
I was thinking about that also , and definitely will test that theory for sure, but do you think less than 18 inches run can create so much momentum? ( code max 24)
I’m attaching pictures to show you water flow under full open faucet, which is not that powerful at all. I can position water flow a little bit off the center ( I have the one that allow change of water flow direction 6-8’).

DD940A41-F9AA-45EB-9593-E56B887E4B23.jpeg
052615B2-7121-4060-97BA-4E3EFA5785B6.jpeg
 

Attachments

  • 6DC92E9E-9AC1-4DE7-B38F-A7900AABFB16.jpeg
    6DC92E9E-9AC1-4DE7-B38F-A7900AABFB16.jpeg
    35.2 KB · Views: 212

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,412
Points
113
Location
IL
I was thinking about that also , and definitely will test that theory for sure, but do you think less than 18 inches run can create so much momentum? ( code max 24)
Another test you could perform is to snake some clear tubing through the trap to measure the pressure on the other side of the trap. That is cheap and easy enough to try if you are interested. Now that I think about it, I think I would try that first.

If you know somebody on oxygen, they throw away suitable tubing every month. The tubing is also cheap at hardware stores.

If that has too much pressure, then a regular trap would not be able to hold the gas back.

EDIT... Oooh... how about putting in a Transparent P-Trap as a test! Perfect job for that. You can see if the problem is the trap emptying due to flow, or pressure. Pressure, even when it is not enough to break the water seal, would be seen as a difference in waterline levels on each side of the trap.
 
Last edited:
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks