Smell from basement traps

[Olton]

Hello,

I've been getting odors from the traps under the sink basins in the basement - I assume they're getting sucked dry, despite daily use, but don't know enough to narrow down the cause. A plumber has already made two modifications (detailed below) but it hasn't resolved the issue. I'm still waiting back on them, so I'd like to be a little more informed in the meantime.

The laundry room sink gives off a powerful funk of stale detergent and BO, while the bathroom sink can reek of urine. There seems to be a negative pressure airflow in the middle of the basement, as it carries the odor around when the ground floor windows are open. It's definitely less noticeable when the windows are shut and the A/C is running.

There's also a floor drain that, at one point, was giving off toilet odor. The plumber placed a sort of diaphragm to stop it, yet allow water to drain if necessary. That seems to work there, the other fix they made was an air admittance valve at the laundry room sink, which doesn't seem to have done anything at all.

The house is a single ground level, with a furnished basement. There are two vent stacks on the roof, and all fixtures are within five feet of one or the other. (I might guess that they are 'wet vented' at the basement level.) One stack seems to service the bathrooms on both floors, while the other is above the kitchen, with the laundry room below that. I've cleaned an old bird's nest out of the one above the kitchen/laundry, snaked out some debris, and flushed them both with water.

Both the kitchen and laundry sinks still gurgle when draining or running, even after flushing the stacks. There is a dishwasher alongside the kitchen sink, and I'm thinking it might be a factor for the odors after it's been running.

The weather might also play a role, with the odor seemingly more likely on windy days even if no precipitation falls. The house is north-facing, with an east-west roofline, using 6" - 8" stacks on the south slope. The wind mostly comes from the W/SW.

Just trying to give as much information as I can - Any insight into this problem would be appreciated!

 

[Smooky]

Some pictures of the plumbing such as under the sinks that gurgle and where there is odor etc might help. Are the pipes exposed in the basement? Do you have a septic tank or does the waste water go to the sewer?

 

[Sponsor]

 

[WorthFlorida]

Sounds like to me there still is blockage. I assume this problem started recently and you have been in the home for years. You might have two or three drains feeding to one stack and the vent pipe leading to the vertical stack runs horizontal. So flushing from the roof down and the water hits an obstruction, it will then flow horizontal to the next drain.
Example; Toilet, sink, and tub with the sink in the middle. Assuming the sink has the vent pipe running vertically from its drain, then the toilet and tub vent pipe would run horizontal. If the sink has the block the water would back up the vent pipe until it gets to the toilet or tub vent pipe and the water would flow to one of those drains.

What type of drain pipe does the home have?

Check this out, it explains a vent problem shown on YouTube,. Start at the 13:15 minute mark.

 

[Olton]

Thank you for your quick replies.

I've lived in the house less than a year, and the problem was noticed within a couple months. It was built in 1958, and seems to be a mix of galvanized and PVC, mostly behind renovated walls. The waste goes to a sewer, no septic.

Attached, are the two sinks that gurgle. The odor comes from the third picture.

The first two pictures are underneath the kitchen sink, while the third is underneath the laundry room basin. I marked it with a few lines for clarity - blue is the sink drain, cyan the washer drain, yellow leads to the vent (which also appears to be the kitchen drain) and orange is the air admittance valve.

Edit: I've added a quick diagram of how I think everything is set up:

 

[Olton]

Just an update -

I've removed the bathroom sink, and found two clear rubber tubes going from behind the wall into the drain line. If I had to guess, they're a cheap attempt at venting but I'm skeptical of its effectiveness. Has anyone seen something like this?

There isn't anything on this side of the house that would need a condensate line and the tubes seem quite dry. I don't know where they go yet, they're taped solidly in place, through the vapor barrier behind the paneling.

Regarding the odors, all traps appear to hold water, and I can definitely see water in the shower drain trap. (I recently noticed it will have odor issues as well.) However, I get a stronger odor from any of the problem fixtures after the trap is disturbed (such as running water into it,) as if it kicks up the odor below and lets it come up. The laundry room is not connected to the bathroom side, and it appears to be properly vented through an air admittance valve, so I don't know that I can blame this side's odd setup by itself.

Does anyone have an idea what's going on, or a suggestion for the bathroom venting?

Thanks for your time.