Sewer smell when washing clothes

[Skorbel]

I am visiting my parents home for Thanksgiving and I've learned that they have an issue with their plumbing where there is a foul smell every time they wash clothes. This smell does not occur when washing dishes, showering, flushing the toilet, or anything else but using the washing machine. I confirmed the machine itself does not smell by inspecting it with my nose after the smell cleared out (hours after washing clothes).

I've attached pictures from the washer to the wall, and then also all the piping in the basement. I'm a IT professional and not a plumber but I don't see where there is a trap to stop gasses coming back when the washer pushes water.

[edit] I've traced the path of the pipe with a red line to make it easier to know which pipe i'm talking about.

Thoughts?

 

[Jadziedzic]

You'll need to remove some drywall from the area below the washer connection box so you can see if there's a trap within the wall (as per code) with a vent connection. If not (i.e., the drain line runs straight into the basement) adding one will likely resolve the problem.

 

[Sponsor]

 

[Cacher_Chick]

Yes, the trap is required to be on the same floor as the washer, and it must be properly vented. It is hard to know what you have there without looking inside the wall or running the line with a camera.

 

[Reach4]

ut I don't see where there is a trap to stop gasses coming back when the washer pushes water.

The trap for the washer standpipe is in the wall under the box shown in the WasherToWall.jpg picture. The smell may not be coming out of that area, but it might be.

I suggest isolating each area with a thin plastic dropcloth (such as https://www.walmart.com/ip/Husky-Plastic-Drop-Cloth-0-7-Mil-3-Pack/17217856s) , with masking tape to help if needed. Do a load of wash, and let things sit. Then lift each plastic to sniff to see where the smell is strongest.

Have you already isolated the smell to the basement, or is the smell as strong upstairs too? Check the laundry tub, floor drains, softener drain standpipe, AC drain, or whatever.

Is that a sump and pump to the right of the stairs in basementwalltodrain2-jpg? Isolate and sniff that too.

 

[Jadnashua]

Depending on how the drainage lines are run, because the WM has a high flow rate, if things are not vented properly, it can siphon other traps dry. This can allow those nasty sewer smells to get into the house until you run some water in those places to refill their traps. Without a good understanding of what's there, there's no reliable way to tell where or why it is coming from or happening.

EACH fixture needs its own trap (with few exceptions-say a double sink, for example) and each trap needs to be vented properly for everything to work well.

 

[Skorbel]

The trap for the washer standpipe is in the wall under the box shown in the WasherToWall.jpg picture. The smell may not be coming out of that area, but it might be.

I suggest isolating each area with a thin plastic dropcloth (such as https://www.walmart.com/ip/Husky-Plastic-Drop-Cloth-0-7-Mil-3-Pack/17217856s) , with masking tape to help if needed. Do a load of wash, and let things sit. Then lift each plastic to sniff to see where the smell is strongest.

Have you already isolated the smell to the basement, or is the smell as strong upstairs too? Check the laundry tub, floor drains, softener drain standpipe, AC drain, or whatever.

Is that a sump and pump to the right of the stairs in basementwalltodrain2-jpg? Isolate and sniff that too.

That is indeed a sump pump. I ruled that out because it only happens when they wash clothes. I'll try to figure out if there is a trap behind the drywall.

Thank you everyone for your suggestions!

 

[Jadnashua]

There's probably a trap, but what is important, is if you can find which drain smells, to verify that that particular trap is vented properly.

 

[Skorbel]

There's probably a trap, but what is important, is if you can find which drain smells, to verify that that particular trap is vented properly.

Tomorrow morning we'll start a load of wash and position ourselves around the drains to see if we can pinpoint where it is the worst. The smell also travels upstairs but I'm sure that is from the smell getting sucked into a cold air return or something.