We have been having a problem with a bad smell that we think is sewer gas coming up through the shower drain when we flush the toilet in our back bathroom. We're not having the problem anywhere else in the house and at first we only noticed the smell, like I said, when we flushed that toilet. The last couple of days now, I am noticing the smell in there all the time and it seems to be getting stronger. We have a mechanical treatment type sewer system with an aerator pump and I called the installer first but they said it's not a problem with the sewer system and that we should contact a plumber. After reading old threads I did run water in that drain but it doesn't seem to help. I now seem to be noticing the smell in the sink of that bathroom, too. Any suggestions?

speedball1

Sewer gas can only get past a trap if;
(1) The trap seal is reduced down to where sewer gas escapes, or
(2) You have a partial blockage and when you discharge a toilet the liquid hits the clog and bounces back sending a bubble of air ahead that belches out of a fixture trap.
My bet's on door #2. Snake the lavatory vent from the roof, put out enough cable to get out of the bathroom and then run a hose down the vent to flush the line out. If that fails then snake out the shower from the drain and get all the rotting hair and grease cleared out. Then pour a 1/2 gallon of bleach down the drain and let it set overnight. Next morning flush the line out with 2 large pans of boiling water, (this is important) The bleach will start to eat the hair up and make it slippery and the boiling water will melt the grease and flush the entire mess out into the main. Good luck, Tom

RIRED

Were you ever able to figure out the problem - I have the same exact issue. Thanks

Milo Dolezal

When you flush toilet - the sewer system sucks air in. It doesn't push it out. Look for the source of the smell problem somewhere else - like dry traps, bacteria inside your shower drain, open plumbing vent pipe, ... etc.

speedball1

Did you read and follow my earlier post?