ODD Sewage Odor--Need help to detect source

[DG]

My elderly parents really need some help. They detected an odd sewage smell in their 12 year old detached home in Boynton Beach, FL. They are on a sewage system. There were no back-ups, no other obvious plumbing problems or leaks, no drainage issues. The sewage smell is coming from only one area of the house, in the front, near a bathroom, but more strongly from inside a closet. They cleared out everything in the closet and did not find any dead animals or anything that could cause this odor.

They had a plumber come out and "send smoke" through the sewer line and did he did not detect a leak. He claims their plumbing lines are fine. They had the area tested for mold, which is negative. They had the HVAC system (brand new) checked for leaks (even through the attic) and nothing is leaking or wrong there.

They do have a powerful back-up generator on that side of the house which runs on liquid propane in an underground tank. I am wondering if this could be the culprit? Or what else could cause an obvious "sewage odor"?

ANY ADVICE iS GREATLY APPRECIATED. PLEASE HELP US SOLVE THIS MYSTERY!!

 

[ncplumber]

I would say that propane could be the culprit. Propane has a distinct garlic type odor, sewer gas has a distinct odor, and another popular culprit is a dead mouse. All can really wreak but to a "trained nose" can be distinguishable. I used to live in that area of Florida. Try to find a plumber by the name of Kenny Tuttle. He's a really good plumber and very experienced. Last I heard, he lived in the Palm Beach County area. Tell him Harvey's son said hello if you find him.


Best of luck!