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?

