Laundry room smells like sour water

[cjh]

House is on private property hooked up to a 2 year old septic system.

We don't have a washer to our laundry room drain. This weekend I noticed a sour smell from our laundry room. I thought it might be a bucket, mop, etc. I cleaned all these things out. This smell only occurs whenever the bathtub drains or the dishwasher drains. Last night I finally figured out the smell was coming from the washer drain in the laundry room. This pipe sticks up about 6 inches.

I'll submit a picture of this pipe so one of you can tell me if this is the original laundry drain pipe or not. This house had a lot of modifications that the seller corrected, but I am thinking this might be a pipe that doesn't have a trap or vent and it connected directly to the main drain line.

There are two bathrooms on opposite ends of this house. The laundry room is in direct line with the main drain line. The smell is worse whenever someone takes a bath in the tub that isn't used everyday. But this morning the smell was slight whenever the dishwasher was used. The problem is worse in cold weather and not in milder weather.

[Koiflowers]

Until you get posts from the experts, at least put a baggie over the top of the pipe and rubberband it closed, so sewer gas isn't getting into your house.

[Greg]

Try pouring water down the drain, It could be that the trap has dried up. Traps require water in them to prevent gas from coming back up through the drain. Greg