Hello all, and thanks in advance for any help you might be able to give on this subject.
In the last week, a foul sewer type odor fills our laundry room whenever we do a load of clothes. I know that this could be a blocked trap, and that the trap is intended to keep the smell out of the house via a water seal in the bottom of the trap. I also know this could be a dangerous situation and needs to be fixed quickly. My problem is in identifying and getting to the trap.
I enclosed 2 pics ( I hope) in and below the laundry room in the basement. On the far right of the basement pic there are a hot and cold pipe going into the garage. There is also a drain pipe between them, with a cleanout on the end (difficult to see in the pic). To their left, in the narrow space between the floor joists, are the hot and cold for the washer and, since there are no other H/C pipes in the area going up through the floor, for the laundry tub as well. I assume there is a split in the wall to feed both?? I assume the drain on the far left is for the laundry tub.
Neither drain pipe is directly under the washer drain in the upstairs wall, AND neither look like a trap to me, wherein lies my confusion. I can open the clean out on the far right, but how does that help me get to a trap that appears not to be there? Or do I have any idea what I'm talking about?
Responses are certainly appreciated.
Mart

[www.dropbox.com]
[www.dropbox.com]

There is a tee in the wall that catches the trap , also in the wall, and the vent extends on upward thru the wall. To clean the trap you go in where the drain hose from the washing machine goes. Although I highly suspect a clogged trap is not the problem. A clogged trap would prevent the washing machine from draining.

OK...makes sense to me..no problem with the washing machine draining. In reading some of the other posts on similar problems, I have a drain in the basement, about 20 ft from where the piping goes up to the washing machine. There is a bathroom between the two areas, and the waste from this bath is pumped up to the septic tank. This bath is very seldom used, and there is no smell either there or at the drain. Does the very very limited use of this bath, and therefore the pump, have anything at all to do with the odor we're getting??