My husband and I have a 6 mo old modular home. In the past few weeks, we have noticed a rotten egg/sewer smell inside the house. It seems to happen most often when the A/C is on, although in at least one instacne, the A/C was NOT on and the smell was awful. The smell seems to be concentrated on the 1st floor in the MBR/MBA and in the cold air return. The builders have ripped holes in the floor and walls to check all vent/drain pipes and everything is hooked up properly. They moved onplumbing stack closer to the peak of the roof thinking maybe the bathroom vents were pulling the gasses back into the system. The basement floor drain has been flushed and all of the sinks, showers, etc are used daily. There is NO smell in the attic. The septic guy has been out, too, and can find no evidence of a septic prob (i.e., no sinkholes, grassy patches, etc) We are mystified. I know absolutely NOTHING about plumbing, but I do know our 2 small kids (less than 2 yrs) are having some weird health problems and I’m afraid they may be related to this! Help! Any thoughts are greatly appreciated! Thanks in advance. Gayle
Your AC system may be sucking in gases from your venting system. Plumbers will typically extend the pipe of the vent systems to get the gases away from the AC system. You may do this or look into charcoal activated vent pipe filters. On the web search engines type in “septic odor” and you should find a few solutions of this type.