I have read all of the forums posted on this subject, but none seem to relate to my exact problem. My dad and I built this house in 2002. The plumber we hired was very good. My plumbing is all in the concrete slab. However, I am getting a sewage smell throughout the house with no obvious source. At first I thought it was coming from the utility room, but now I'm not sure. It doesn't seem to happen in relation to running water. It does seem to be really bad first thing in the morning and late at night. It also seems to be getting worse. We have a septic system and city water. I feel like I am going to pull my hair out because I try to have a clean house and here it is smelling like a sewer. I tried pouring bleach down the drain that is at the end of the line of my plumbing and then flushing it out real good. If nothing else, this seems to have worsen the problem. I'm not experiencing any clogged drains, but I am wondering if maybe my septic system just needs to be pumped. Please HELP!!

Is there a floor drain in the utility room? Check it out and pour water in the trap. Smells are difficult to track down when you're not there but I can give you some places to start looking.
If your septic tank is full and needs to be pumped it's possible that a discharge hitting a full tank could send a "bubble" of sewer gas back up the line. It will smell worse at night and early morning before the sun comes out because the air's heavier and the sewer gas will sink down instead of raising. Once the sun warms things up the air raises and so does the gas. Let me know what you find. Regards, Tom

Hi,
From smelling this myself, there is nothing worse in the world than having these smells in the house!
I experienced the same thing, and found out it was coming from a shower we hadn't used in a long time. The trap beneath the shower had "dried up", no water in it. When the atmospheric pressure drops, it allowed these smells to come right up through the shower drain.
I know it sounds like a "long shot", but if you have any drain in your house that hasn't been used for quite a while, pour about a quart of water in it, see if the smell stops.

The drain hose for the washing machine is just sitting in this hole that goes directly to the sewer pipes underneath the slab. There is no seal around this hose, so I think the gas is coming up through it. I opened a window that is directly above this hole and the smell is gone. Does this sound like a normal way to drain water from your washing machine? Is there supposed to be a seal around the drainage hose to keep that gas from coming up through it?