So we bought our house a year ago.. that is how long this has been going on without figuring the problem. We have had 3 plumber's out to try and find the problem. No one knows. When we use the washing machine, dish washer, or master shower, the smell happeneds. We tried making sure we where spacing out the time of washing clothes, didnt work. There is no backup, just the horrible smell. The only place the smell comes from is my daughters shower drain. No where else. It's so bad some nights she has to sleep in the living room . We open the bathroom window to try and get the smell out. Normally within 5 hours of finishing washing the smell is gone. A little more background... When we bought the house the owner had the leach field redone. The plumbers that come, have scoped the septic tank and say its fine.. not even 1/4 full. I was told they looked at the vents on top of the house and those arnt clogged.. The shower drain has NOT been scoped.. The home is about 40 years old. The lady that lived in the house before we bought it was disabled and I dont think she ever used the bathroom where the smell is coming from. We are on 4 acres. no neighbors close. We dont have an attic or basement. So why is it 3 professionals can't find our problem?? We are tired of spending money on plumbers and not getting an answer. I have researched like crazy without answers. Please someone help.