I'm having a problem with sewer gas venting into the house. We can't determine where the gas is originating except from the basement. It comes mostly from using alot of water at one time. Such as: 2 showers and 3 wash loads. The smell is at it's worst when the wind is from the South and West (vent is on the W slope of the roof). We have a septic system and the house is 30 yrs old. This has been an on going problem since we built. We recently had the basement permasealed with an enclosed sump pump. The smell was much better a year ago when the basement was sealed for leaks in the foundation but now the odor is back.
I have a septic system but don't have any issue with the drains not draining. I was going to have the septic pumped but the septic company said they didn't smell anything when they opened the cap. We can't figure why it's a problem and why it is worse when there is a South/West. Any ideas??