We've been renovating the basement, gradually turning it into a livable space, and now we've hit a wall with this mysterious shower issue. We hired a plumbing company to install a toilet and shower in the area that will eventually serve as a bathroom. After having numerous issues with the toilet that have finally been remedied, now the shower is causing problems. Every time it's used in warmer weather, sewer gas is emanating from *somewhere*, but it only ever happens when the shower is in use. The higher the temperature outside, and the rainier it is, the worse the sewer odor gets. The trap beneath the shower is working fine, no issues there. Does anyone have any idea why this is happening, and do you think installing a vent directly above the shower would remove the offending gases?

How are the shower and toilet currently vented? What problems with the toilet were you having?

Negative Pressure in your house could also be responsible.

Best Wishes

Steve:
I was told that it's connected to the main stack that everything else vents through. Does that make sense? There were leaky seals on the toilet connection, apparently.

Wheelchair:
Sadly, that doesn't sound fixable. The shower isn't connected to the sewer, or so I've been told (the source of that info may not know WTH he's talking about, but I can't tell him that). Not sure if a connection to the sewer is necessary for negative pressure to occur.

Thanks for the responses!



Edited 1 times.

It sounds to me that your drainage was not vented properly. Its possiable that they wet vented your system. This will cause the trap to sifon everytime water is ran from upstairs or if the toilet next to the shower is flushed. One way to check is to have someone upstairs flush a toilet while you check the water in the trap. If you see the water bouncing or the water level decreases you have found your solution (venting)

Good Luck