Sewer gas issues

Greetings! Got a sewer gas issue in a downstairs bathroom. Layout is this from left to right: bathtub, toilet, double vanity sink. Then a half bath right next to it with another vanity, then toilet. I have replaced wax seals on both toilets, but this hasn't seemed to help. It seems that the smell is coming from under the vanity sinks on the right. I have made sure there is water in all p-traps and roof vent is clear. One plumber came out on a day when there smell wasn't particularly strong and didn't seem to notice it much. Suggested taping sink drains to try to eliminate and identify source of the smell. This hasn't worked. Smell hasn't really gotten better or worse. All three sink drains are taped, wax seals replaced. There are no studor vents under the sinks. Any thoughts, ideas? Thanks! G$

The smell might not be sewer gasses...

Is it strongest at the vanities? If so, you may have crud buildup in the overflow. Do you have particularly long drop to the p-traps? Is each sink got its own trap, or is there a long arm connecting them to one trap? That extra length of pipe before the p-trap can get accumulations and smell.

It's not unheard of that a lazy plumber and a poor inspection left a vent incomplete in the wall. If it smells when the window is open, the height and location of the vent stack on the roof may need to be addressed. Lots of things can smell nasty, and they aren't sewer gasses.

Not necessarily strongest at the vanities. As you know it can be really hard to tell exactly where it's coming from. Each vanity has its own p-trap. They're not connected. I've also cleaned out the traps, etc. No smells there while I was cleaning them out either.

You might want to try to clean out the overflow channel of the sinks.

I would check the attic if you have one, see if the vent goes all the way out, also check the fart fan hose, make sure it is connected, check the vent pentetration through the roof, make sure it isnt clogged with leaves, etc. run a hose down the vents for the bathroom, make sure they arent blocked. You might have a vent leak inside the wall.

Is it a raised foundation? Maybe you have a sewer leak in the crawls space?

If you were closer I would lend you my Jack Russell Terrier. She can pinpoint where sewer gas is originnating Immediatly.

You can't get her nose away from a toilet base with a poor sealed wax ring.

Checked stacks on the roof. There is a 2inch coming out of the roof that services the bathroom and it is quite smelly--compared to the 3inch that serves the other side of the house (no smell at all.). Unfortunately it started raining on me before I could really investigate much ....Pretty steep pitch and metal roof! It seems like there is a turn or two in the stack about 2 ft after it enters the house. Best suggestions/cautions for snaking out this vent? Thanks!

It might help to have your plumber do a smoke test, or peppermint oil test, on the drain system.



One thing that has not been mentioned: find out where the condensate drain from your A/C system is. A faulty hookup can have sewer gas drawn into the ventilation system