I have not submitted a question here before but found such useful information I thought I'd give it a try. We have a new home that we moved into 2 months ago and have run up against a very puzzling problem. We have had a bad, intermittent sewage odor at the front of the house since prior to closing. It was so bad at one point the private inspector we hired just prior to closing suspected it could be a dead animal under a pile of rock and rubble that has long since been cleared.
The odor is a sewage odor, or methane related gas odor. We were smelling it early in the mornings, from about 6:00 AM - 9:00 AM, and in the evenings from about 5:00 PM - later but now we are smelling it more in the evenings. We never smell it in the mid afternoon. Our home is in Austin, TX if that helps.
We suspect the odor is methane gas coming from the plumbing vents which are at the top of the house and the gas is filtering down to the front of the house. Not sure if that makes sense, but that is all we can ascertain at this time. This is a 1.5 story house with 2 baths up and 2.5 baths down. The smell is isolated to a general vicinity right near the front door and front side walk when it is present. The strange thing is it does not smell every day, and some days the smell is stronger than other days. We asked the plumbers to come and investigate and they did a "smoke test" to look for any unsuspected leaks in the plumbing vents. In addition they ran a camera servey to look for cracks in the plumbing lines. They told us it was not a plumbing problem as they found nothing unusual. They told us it might be the dirt in the beds at the front of the house, or something perhaps as arcane as buried rotting tree roots in the front beds, however I believe if this were the case it would smell every day throughout the day. We also asked the city to come and investigate to be sure there was nothing happening at the street, as this is city sewer, although we suspected this was not the issue since we never smell the odor close to the street. A few times we have also smelled the odor at the back of the house just off the patio, but only a couple of times in that location. Mainly it is at the front of the house near the front entrance and limited to a very distinct 100 - 150 ft ft radius, which by the way is not far from the plumbing pipes. I have read that Extending the plumbing vents higher on the roof or installing a wind block at the vent tops might help, if in fact the smell is methane gas coming from the plumbing vents. I also read that possibly installing a deflection device (much like an upside down chimney cap) on the tank outlet tee may resolve the smell. We are hoping someone may read this and be able to help us. Our builder is coming to take a look this week but if the smell is not in the air when he is here we are afraid he will be uncertain where to look next, especially since the original plumbing contractor has wiped their hands clean of it and given a clean bill of health report back to the builder.
Please let me know if I can provide any additional information. I'd be glad to. I am so hopeful that all of you out there may be able to help us as the original plumbing contractor has not.