About a year ago my husband and I along with our two daughters moved into a three level home... here and there we have to plunge the basement .( this was mentioned to us to by the landlord).. the past 6 months its been about I to 3 times a week we have to pluge and snake the basement sewer... we have spoken about the situation to our landlord... the smell is horrible... every time the basement sewer line gets backed up we bleach the basement floor to rid any left over bacteria and to assist the smell that wafers throughout the line ( granted we also use those flowerly smells along with vinigar, and baking soda to help also -- but not at the same time)... the area where the sewer line sits the room above it is the living room... that area can smell horendous even when the basement is not backed up... we have looked for mildew and mold to see if they could possibly be a colperate too... what else could cause this sulfer, sewer , smell?.

Sewer gas and sewage backing up this much should get your landlord in a heap of trouble. Let him know in writing hand delivered or certified mail that he has 3 days to get a plumber in there or else the Health Dept is your first step along with putting any future rents in escrow with a lawyer or tenant rights legal aid place.

Sure there is probably mold and mildew too but sewage always smells that way - human and food waste produce gasses and they aren't good to breathe long term.

Warning you before you rented is no excuse for his lack of attention to this.

I'd push this with the LL and not try anything on your own. Tell the LL you find this situation NOT HABITABLE and want the Health Department to inspect to do a determination. I think the LL will get a move on