We have this bad smell from our sump pit, usually during or after it rains. We’ve had several plumbers in to check for the cause with a few different opinions. Some have suggested to replace the entire cast iron pipe under our basement slab and others recommending just replacing a section but no one can guarantee this will fix the problem.
We have an overhead sewer system with the 1st floor going into the sewer line through traps. The basement bathroom has a sink & toilet piped into the ejector pit along with the laundry sink and floor drain. The washing machine dumps water into the laundry sink. The ejector pit is located centrally within the house and the sump pit is at the far back corner with the drain tiles on the outside of the foundation. There is a drain to the tiles located at the base of the cement stairs leading to the basement door. The overhead sewer line runs along the wall and towards the front, turns downward & goes under the basement slab before running down the center of the basement out to the back of the property, which is where our sewer lines are.
We had this line inspected by camera several times and no one can determine the cause of the smell. We have had a 4 foot section of pipe replaced near the back wall where the old cleanout was located. The smell went away for two years before returning this year. The plumber dug back into the slab to check his connections but found no problems.
Recently we have been experimenting with soap suds in the ejector pit and upstairs sink. Sometimes they appear in the sump pit, but not all the time. We have had the ejector pit replaced but the problem still exists.
If it rains, the smelly water runs into the pit. If it hasn’t rained in a few days we also sometimes see water running into the pit. I have sealed the sump pit with clear lexan to minimize the smell and ran the pipe out 40 feet to the backyard.

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put some flourescent drain dye into the basement plumbing to see if it shows up in the sump.

What was the reason for the cast iron replacement in the past? If it was deteriorated and leaking under the slab, you may be experiencing the same thing again from a different place. Can you eliminate all under slab drains and wall hang the sewer to the point where you can transition back to the point of the previous under slab repair?

Thanks Packy,

We've tried half a gallon of bright green dye a plumber left with us, but nothing showed up in the sump pit.



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JLNY

We replaced a section of the cast iron because the first plumber suspected a break in the pipe at that point. The camera showed a slight misalignment and that worked for a couple years. Subsequent plumbers have snaked the pipe and cannot positively pinpoint the area that needs replacing. Is there a way to isolate the area where the crack or opening is at underground besides seeing it on the camera? I've read about using inflatable plugs used for pressure testing new plumbing. Can't I do something similar by plugging the lower end at the cleanout and pouring water into the pipe from the other cleanout to see if it leaks out over say a couple hours?

You can certainly try plugging the drain at the clean out. If you fill it with water and the level drops, you know there is a break somewhere, but you still don't know the exact location.

it no dye showed up then that is very strange. ground water does not smell.

I'm not a plumber but for a second I thought I was reading an old post I had written. i have a a drain at the bottom of cement stairs (basement to driveway)that ties into sump pit (8 feet away). I have an ejector pump for a basement bathroom although my utility sink (collects washing machine discharge) now feeds a pump bucket that connects to overhead sewer barely downstream of where ejector pump connects. Our sewer travels along side wall and drops a couple feet and exits through the front basement wall around waist level. In the front yard it gets a couple feet deeper and travels 15 feet to the left to connect to city main under the street.

The first 5 ft going through the front basement wall is ductile metal, the next 5 ft is PVC and then it connects to original clay tile (from 1953). We went on a 6 day trip last winter and a few days after we came home our sump smelled like sewer and was going off as frequently as once every 70 seconds. We just had the sewer line done last July so I was pretty distraught. Called back the same company and they confirmed a clog (could tell just by looking down the new cleaout in the front lawn. They rodded to the street and haven't had a problem since. I never asked but I suspect the plugged line was leaching out of the clay joints (porous cement) every two feet and finding it's way back to the drain tile. i posted pics of the metal to PVC and PVC to clay connections and it seems the work was done properly. We have a belly in our clay section between the sidewalk and the street and we have a "lip" where our pipe connects to the main in the street. The cold weather and lack of water flow for six days probably caused the clog. I now constantly flush water with ejector pump and washing machine pump bucket to prevent solids accumulation. Going on 11 months without a clog or smell.
It's baffling that the dye didn't show up especially because you may have saw soap bubbles. So who knows but I thought I'd share my story just in case



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