My problem is, when we do laundry there is a sewer smell in the basement. The following is a summary of the conditions:
Two story home with a half basement.
My problem is worst when it is raining.
The area were I believe the smell is coming from is very busy.
There is a sump pump in the area, but I do not believe the smell is coming from the sump pump. The only inlet into the sump pump is from condensation of the furnace. Also I taped the opening up and I still smelled the order.
The septic is located approximately 15'-0 from the house, but I have a half basement & the inlet from the basement into the septic is approximately an additional 15'-0. I do not think the smell is coming from were the piping exits the house. But I may be wrong; I'm running out of options.
There is a toilet directly above the area of the smell. I did put duct tape at the exit point of the down pipe, which did not help, but I wanted to try something. Also I do not receive the sewer smell upstairs in the area of the toilet.
The septic has been pumped sever times, but I do not think that is the problem either, because after it gets pumped it still smells in the basement. Also I believe we have a double tank, but I believe is has only been pumping one of the tanks. The septic guy believes I may have an air vent problem. He may be right. That may be my next step is to have someone check out or clean out the air vents on top of the house.
The other possibility is there is also a duct pipe going through the basement wall at this location. I nave calk this area up pretty good, but I still get the smell. This may be there problem.
I had one plumber over and he had no idea.
I do not mind paying somebody to fix my problem or to determine what my problem is, but I do not know what type of expert to ask.
I'm asking for any help here.

Sorry it is sewer odor not sewer order

Hey Danny,

The reason the smell increases when it rains is that sewer gas is heavier then air and the humidity when it rains makes the gas sink lower and concentrate,
Hense, the stronger smell. Mystery cleared up?
I only wish you "sewer odor" were that easy. Smells and noises are the hardest to track down when you're not there to check it out in person. The only thing we can do is point you in the right direction. Having said that, the first thing we check is the floor drains to see if the traps have water in them. Next we listen for bubbles or gurgles when something's flushed or drained. Gurgles tell us there might be a vent problem, bubbles would indicate a partial blockage or a full septic tank. In older houses we check the stacks for any cracks or bad joints that may expel sewer gas.
Perhaps some ot the other experts may have other solutions but You really have to be there. Regards, Tom

Thanks speedball1
When I flush I do not get any gurgles or bubbles. I may need to have my stacks checked out. Or maybe I need to better seal off the area were the duct exists the basement. I have thought I should install some sort of ventilation system in the basement (draw the bad air out). I thought I could put a fan on the basement window to draw the air out, but I do not think that will be fixing the problem. I only have one drain in the basement, and all that does is takes the condensation from the furnace to the sump pump, I have run water with Clorox through the basement drain several times and that does not seam to help. What type of expert should I hire to figure out the problem & to repair the problem?

Hi Danny,

"What type of expert should I hire to figure out the problem & to repair the problem?"
A sharp plumber with a good sense of smell. Good luck. Tom

Speedball
I discussed this subject with a builder. He thinks I need another vent / stack from my drain pipe in the basement to the outside of the house. He believes he can add a "t" section within the basement and run it out the side of the house. He is going to get a second opinion from a Plummer. If this works I will let you know.