My apartment has been reeking with a foul odor for a while now. It seems to kind of vacillate between smelling like something died to smelling like a sewer. I'm about to approach my landlord about it but in trying to understand the nature of the problem i was reading about S Traps and how because of their design they could allow sewer gases to flow into a building. I also read that because of this issue they are illegal. This S Trap is in my kitchen where most of the odors seem to be coming from and my kitchen is directly behind my bathroom. As there are other plumbing problems occurring simultaneously, like dirty water flowing back into my bathtub, i'm wondering if this S Trap could be a part of the overall problem?

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  • That trap would not be the problem. You do have a problem if sewage is backing up in the tub. With the waste backing up no trap can prevent trapped gas at the point where the waste fills the trap and flows into the tub, getting the lines cleaned so there is no backup is the problem not the trap.
    – Ed Beal
    Sep 4, 2018 at 1:01

1 Answer 1


Oh my. this trap isn't even an S trap, it's a rollarcoster trap. wow..funny, but not your issue. The reason for the P trap is to trap a little bit of water in the P where stop all air from moving up the pipe. You have a sewage backup issue.

It's very possible this trap also does not trap water if you take off the trap you can see for yourself if it's full of water or not. The suction that S type traps create pull all the water out of the trap like a siphon leaving no water left to block air flow. I have one, i need to get around to fixing. It definitely does not cause any backup.

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