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BigDave, Licensed Service Professional
Category: Plumbing
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Experience:  With Over 22 YEARS of knocking on doors and solving problems.
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Hello, we are having a problem with sewer smell coming from

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Hello, we are having a problem with sewer smell coming from the toilet bowl. Sometimes it is so bad, it drifts out into the hallway. After cleaning the toilet bowl, the smell goes away but then comes back after about 4 days. After cleaning again, the cycle repeats itself. What can we do? Help!
If your toilet is loose and rocking, you probably have a bad seal under the toilet at the wax ring. Drain tank by flushing after turn off water valve, force water through trap with plunger, disconnect water supply and take up the toilet to replace the wax seal. The flange should be at finished floor level to provide the best seal. If the flange is lower than the finished floor, we will need to talk some more.

Edited by BigDave on 12/6/2009 at 4:47 PM EST
Customer: replied 6 years ago.
Hi "Bid Dave"...toilet is not loose or rocking
The wax ring seal can still be faulty. In most cases, this is the cause of sewer gas invading the home. Have you had any sewer backups recently?
Customer: replied 6 years ago.
No recent sewer backup recently...had one almost a year ago. We moved into this house in February 2007 and replaced the toilet shortly thereafter. I've heard something somewhere about the "trap" being dry...does that make any sense?

Yes, this makes sense! How much water is in the bowl after the flush cycle and the tank stops filling? If the water level in the bowl goes down after a long period of time, you could have a crack in the trap that is letting the water in the trap to leak out. Once the level of water drops, the "seal" of the trap is no longer stopping the sewer gas from coming back through the toilet & into the room.

Customer: replied 6 years ago.
Ok, my husband verifies that the water level does not drop (he's the first to use it in the morning). Why would the smell go away for a few days after I clean it and then come back until it's cleaned again? Other than re-installing the toilet, do you have any other thoughts or other things to do?

At this time, I would have the toilet re-installed on a new wax ring. During this process, verify that the flange is resting on top of the finished floor (proper height) & has no cracks or breaks, you may have to clean up the old wax for a good look. Sometimes the flange will end up with an almost invisible crack, that when the toilet is remounted, the tension of the bolts cause it to expand, thus letting gas escape into the room. As far as cleaning goes, it is possible some solid waste has gotten up under the rim, but this is rare and has a different smell compared to methane (sewer) gas. If no solution is forthcoming, a professional smoke test (performed by a plumber) of your sewer and vent system would give defined answers as to where the gas is coming from. Just curious, is your house foundation Pier&Beam or concrete slab?

The diagnosis of bad smells is without a doubt the hardest service call there is!

Customer: replied 6 years ago.
What is pier & beam? our foundation is concrete block
pier and beam foundation will have a crawl space under the floor for access to your plumbing. piers (cylindrical columns) of concrete would support beams of wood. Your sub floor would rest on the beams. OR you might have a basement...

Edited by BigDave on 12/6/2009 at 6:22 PM EST
Customer: replied 6 years ago.
I have one last could the seal and flange be a problem now after almost 3 years from the initial installation? Thank you very much for your assistance, and hope you have a Merry Christmas! Diane

Your sewer pipes are not attached to your house. After long periods of time the house moves (settles) and plumbing gets loose, comes under stress, corrodes & generally starts wearing out from day one. I could write a book about the many causes of pipe & connection failures I've seen in 22 years on the job. Merry Christmas to you and yours as well & good luck.


P.S. have the wax seal replaced first, then if the problem persists, have the smoke test done.

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