Hello! Thanks for reading my question. We're a 2-story office condo in Raleigh, NC that has been experiencing intermittent issues with sewage odors. The odor used to occur a time or two per month, but is now occurring much more often (several times per week). The odor can be at a different place in the building each time and it will be at random times throughout the day. The only real pattern with the time is that when the building is empty (weekends, nights) the smell is often at its worst. The water itself smells fine.

We have had 3 professional plumbers and a plumbing leak detecting service out to investigate. We've done 3 smoke bomb tests with 2 different companies. We've had people check the roof vents. We add mineral oil to the p-traps daily. We flush the clean outs. I'm at a total loss! Any suggestions would be greatly appreciated. I don't even know who else to hire (if the owner will even let us continue- these multiple plumbers have been expensive).

I am all ears for anything that might help. I'm responsible for making the owners of each suite satisfied with the result and right now, I think they want to kill me. But I don't know what else to do.

Are there any vents on the roof near a fresh air inlet?

Yes, we had our AC people and a plumber up there together. They were trying to figure out if the intake vents were bringing the vented sewer-smelling air from the roof vents back down into the building. They didn't think so, but who knows? Maybe it just wasn't happening then? It's got to be something.

Try extending the vents, don't forget to support them