What causes sewer gas oder in a certain part of the house?

If the smell is noticeable mainly around a sink, try flushing a strong cleaner and bleach down the sink's overflow-the small hole(s) inside the bowl near the rim. When the sink fills to near overflowing, water is routed through an inner chamber to the drain. Debris can collect inside the inner chamber, causing odor.

If neither of these measures solves the problem, there may be a small leak in one of the vent lines of the plumbing system, or a small leak around the base of a toilet or other fixture. Check for loose fittings, corrosion, or holes in vent piping. Also, check the top side of horizontal drain pipes. If the top is rusted, it may never leak liquid, but it will leak sewer gas. Drain lines made of copper, steel or cast iron may all exhibit this problem.

When urine and sewer smells persist near a toilet despite careful cleaning, there could be an air leak at the wax ring of the toilet or in the vent pipe. Rotted or damp wood can also cause the smell.

Check to see if the toilet is tightly sealed to the floor. Grab the bowl of the toilet and try to slide it from side to side. It should resist a few pounds of pressure. If the toilet rocks from side to side, the wax ring has failed.

Other than this, perhaps this web page might offer some thoughts as to the source:

http://www.inspect-ny.com/septic/SewerOdors.htm

bg

Not all plumbers are "A" students. Is there a leak in the line under the house? You say in a "certain part of the house", what part - bathroom, kitchen etc.

Are you sure that it is your house & not the neighbors - I don't know how close they are & where the smell is the strongest. Have you flushed the sewer lines? Once in a while they may need to be flushed with about 6-7 big pots of boiling water.

More info is needed to try & narrow down what the problem is espically since many problems are a process of elimination because you are dealing with liquid (which can seek its own level) & gas/vapor.

I work in pest control....wait, hear me out...we frequently have to deal with odor control (dead animals). The thing about odor is that it moves with air flow. Therefore, where you THINK the odor is coming from may very well NOT be where the odor is coming from but a completely different spot.

We had a house last summer that had a terrible odor in the upstairs bedroom. We, as Pest Control Professionals, don't use our noses to track down the cause. We use common sense. The smell was a dead skunk under the front porch. There was no odor anywhere near the porch.

SO.... your odor may be eminating from somewhere else, maybe even outside, or your neighbors house.

Hope this helps.

Since you had a plumber, I doubt my suggestion is helpful. However, something I discovered is that if you have a toilet that is infrequently used the water in the trap will evaporate and the odor will then find its way into your home. Doesn;t matter how clean the trap is. So I just filled the trap and odor was gone.

Check all the drains..maybe the trap in a basement shower or floor drain has gone dry..Pour some clorox water down all the drains..& the odor should be eliminated.

What type of water do you have, well water or city supply water? If it's well water and you don't have a water softner that uses sodium chloride, your water that's standing in your p-traps is absorbing the Methane fumes from the septic system/tank and you are smelling it coming up from the drains.

We have the same problem too. Had the plumber here and he couldn't find the problem either. What we did find out on our own is that this happens whenever we use our wood fireplace, so we close the door to this bathroom whenever the fire is going (big pain in the ***) This I know doesn't answer your question, but I'm hoping to find a solution too.

check the floor drains (if any)