I have had sewage gas smell coming up through a shower drain. It would come and go every couple of days, then got progressively worse. I tried plugging the drain temporarily. I then began smelling it through the tub drain of an adjacent bathroom(but never through the shower drain of the same bathroom). I also began noticing it through the kitchen sink drain occasionally, and nearly all the time through the washing machine drain also located in the kitchen. After reading some other threads I began thinking it could be a clogged vent pipe. Would this make sense with multiple locations?

It sounds like you have no traps. Take a flash light and point it into shower drain. Do you see standing water there ? Back to you. Milo

It sounds like you have no traps. Take a flash light and point it into shower drain. Do you see standing water there ? Back to you. Milo

I have lived here one year, and never had problem. The trap in the shower curves away and is too far down to see. I even tried pushing a rope with a paper towel and could not reach it. I was speaking to the owner yesterday. He told me they had to rebuild a rotting section of the roof, because the bathroom fan was installed to blow into the attic. This apparently caused enough moisture to create the problem. He then tied that fan exhaust into the plumbing vent pipe. Obviously a bad idea. A plumber friend of mine believes this affects the pressure at which the vent pipe operates. Logically if that were the case the problem would exist ongoing. The homeowner also admitted the problem has appeared briefly at times in the past. Getting him to rework the fan properly is not likely to happen. We also ran a snake down the vent pipe from the roof to check for blockages. 25 ft down was clear. Each location ties to one pipe out. Also not a good idea. When the house was built the village code did not allow for vent pipes to be visible on the front roof. This why they had to tie everything to a single pipe on the rear roof.
This morning there is no smell. Maybe it is gone for now. The owner is buying a plug for the drain. I don't know how much good it will do. I believe what ever is causing the problem pushes enough back pressure to bubble up past the traps.
Thanks