Hello,
I've been having this issue for quite a while now. I've been examining the problem very closely the past couple days, and as the title says, when my sump pump kicks on to flush water out, the tub on the main level gurgles and often has a foul odor. The odor can also often be smelled in the basement around the sump pump.

Here's a picture of my setup.

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The red lined pipe carries the water from my tub to the main line. The green pipe leads to the vent on the roof. The orange pipe carries the water from the sump pump to the main line. The connection in the yellow circle came loose recently, I suspect due to the pressure caused by the air backup, but I can't be certain. I am certain the vent pipe isn't clogged. My brother dropped a penny down from the roof yesterday and I heard it land in the main line pipe that leads into the wall in the white wall as seen in the pictures.

If you need any more information, I'd be happy to answer any questions. I greatly appreciate any help anyone can offer!

If it means anything, all on the lower level, there is a washing machine, shower and sink running directly into the sump pump.

Did you connect the pit vent back to the house vent instead of running it out the roof? If so there's your problem. The pit vent is a dedicated vent. Is that's what's happening here? Back to you. Tom

Thanks so much for the response.

I'm not sure, this was the plumbing when I bought the house back in 2010. I don't recall any issues upon first moving in, and none of the piping has changed since then except for the fact that I took the cap off the vent on the roof the other day, as it looked like the cap had plugged the vent completely. This was the suggestion a local plumber gave me for free, as he didn't see anything else immediately wrong, and would have to charge a service call just to remove the cap.

Is the pit vent the one running parallel to the orange-lined pipe that carries water away from the sump pump? This pipe appears to connect to a larger pipe that goes straight up past the bathroom fixtures. I'm not sure where it comes out at. If that piece of information would help, I can investigate later tonight.

It's logically unclear to me why the air would travel directly up the green pipe and come out at the roof instead of just pushing through the much shorter red pipe into the tub, where the gurgling happens, even though there's a water trap there. But then, I don't know a whole lot about plumbing. :)

sorry but my eyesight isn't good enough to follow your pictures. I'm lucky to be reading the posts. Mark will be along and sort things out. Til then. Tom

Hi Pieps!

Unfortunately, there is really a lot of things wrong here!

I'll list the obvious:

1) I see no 4" MAIN CLEANOUT (required by ALL plumbing codes)

2) Cleanouts are missing in other places, too.

3) The tub drain (red arrow) is NOT vented by the pipe you have with a green arrow...not how venting works. Here, a vent must come above the PTRAP for the fixture...see no PTRAP, then the green pipe cannot be the vent. The green pipe probably picks up another fixture (run one fixture at a time in the house if you want to know more). The tub may or MAY NOT be vented above the PTRAP for the tub...can't tell by the pictures.

4) The entire setup for the basement sink is wrong. Here, someone thought it out a bit...installed sink drain and used ejector pit vent to "vent" the basement sink, but then thought more and decided to install a pit vent above the sink discharge drain, but totally show a misunderstanding of sewage ejector vents, plumbing vents and basic venting principles when they forgot that ALL vents must connect, at a minimum of SIX inches above the FLOOD LEVEL RIM of the fixture (sink in this case) for the vent to be a REAL VENT!!!

5) Finally, I can't day for sure exactly what the issue is. I do know that the first plumber should have pointed some of this information out. I do believe that it would be a good idea to get a qualified plumber in to investigate your issue (could be that the MAIN DRAIN (which you have no cleanout to access the drain) is PARTIALLY clogged) AND see if they can help to repipe this up a bit!!

Your thoughts/questions??

Mark

Thanks for the response, it's starting to make a little more sense now how venting works.

I will say there is a big (probably 4") pipe just outside the house at ground level, aligned right where all this is situated. Could this be the main cleanout? I've taken the cap off this and didn't see anything, but then again I couldn't see very far. It seems like the plumber here before took this cap off and was interested in seeing if he saw water come through this larger pipe when the sump pump kicks on. Any further tests like that I can try?

Is the vent leading up to the roof perhaps the larger pipe that runs opposite the purple arrow? That probably makes more sense now that I'm looking at it differently. The green arrowed pipe is likely the kitchen sink, now that you mention it.

Based on what the neighbors say, the guy that lived here before me was a real DIYer. :/

The large pipe outside is almost definitely a main cleanout. I would fill the tub and then have someone drain the tub and flush the toilet while you remove the cleanout and watch to see if water backs up the cleanout...if it does, the main drain (or septic tank if you have one) need attention. If no water backs up, fill the tub and try the test again. If that fails to show water coming up at the cleanout then the problem is more likely a venting problem!


Is the vent leading up to the roof perhaps the larger pipe that runs opposite the purple arrow?


If there is no bathroom above the bathroom in the picture then yes, that parallel pipe is going to turn from a drain/waste pipe to a vent STACK on the first floor!

Back to you...

Mark