Sewer Gas Smell in Basement Bathroom

[Leslie Boseley]

My mother lives in a basement apartment in my house. For the past year she has gotten a sewer gas smell several times. Each time we contacted a different plumber and the smell went away for a time.Nov 97: plumber ran water in overflow in sink. smell went away.June 98: found slight crace and leak on underside of porcelain sink. No odor from there, but replaced sink. Smell went away.August 98: plumber saw sewer flies and recommended floor be torn up between sink and toilet. He thought might be pipe broken under floor. Didnt pursue this option.August 98: another plumber found pipes under sink were loose. Replaced them including trap. Sealed toilet.November 98: Odor returnedOnce it starts, the order is stronger at some times. Cant connect to household activities. The odor seems to be centered at the sink, but that is difficult to tell. Any suggestions on what to try next would be helpful.Thanks, Chris

[Chris MaherParticipant]

: My mother lives in a basement apartment in my house. For the past year she has gotten a sewer gas smell several times. Each time we contacted a different plumber and the smell went away for a time.: Nov 97: plumber ran water in overflow in sink. smell went away.: June 98: found slight crace and leak on underside of porcelain sink. No odor from there, but replaced sink. Smell went away.: August 98: plumber saw sewer flies and recommended floor be torn up between sink and toilet. He thought might be pipe broken under floor. Didnt pursue this option.: August 98: another plumber found pipes under sink were loose. Replaced them including trap. Sealed toilet.: November 98: Odor returned: Once it starts, the order is stronger at some times. Cant connect to household activities. The odor seems to be centered at the sink, but that is difficult to tell. Any suggestions on what to try next would be helpful.: Thanks, Christry running a chlorine based cleaner in the sink, or chlorine itself……..could be a buildup in the trap…… whats your mum use the sink for ?? does the toilet have a vent horn ?? is it faulty and sewer gas comming back through there…..do you have a blocked drain ???DISCLAIMERAll advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed plumber with my own business in Brisbane Australia

[Chris MaherParticipant]

It could be a trap siphonage problem caused by a partially (or completely blocked) vent to the trap. If there is not sufficient venting (downstream)of the trap, a flow of water down the drain could start a siphon action and suck the water out of the trap, thus leaving a path for the sewer gas to come out of the drain of the sink. (OR, could the sink be used infrequently such that the water in the trap evaporates?? – Rare but possible). When the smeall comes back, I suggest carfully removing the trap from the sink and seeing if the trap water level is up to the crown weir of the trap (i.e. the trap is full of water). If so, try looking for a vent line leak or blockage.

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