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Sewage Smell in Basement

Our basement smells like sewage on occasion. We do have a living area and guest bedroom in the basement but are unable to use it at times due the smell.

The bathroom in the basement that utilizes a pump to pipe the effluents to the septic system. This does not appear to have any leaks, all the pipes seem to be sealed and the vent is not clogged on the roof. . Despite our best efforts to locate the problem we / plumber have been unable to locate it.

The smell occurs most often in the winter of when we have extreme weather changes from cold to warm.

Any assistance would be greatly appreciated.

Re: Sewage Smell in Basement

don't know about your plumbing problems but nice foosball table.

Re: Sewage Smell in Basement

Thanks, wish that we could use it more but it is very hard to play while holding your nose!

Re: Sewage Smell in Basement

What you may be dealing with is a dry trap in the sink or another drain. Take a good fsashlight and look into the sink drain when the odor is present; you should see enough standing water to prevent gasses from getting by. If there's a flanged bowl ring installed under the toilet it can direct the flow into the drain, thus not leaking, but still not be sealing at the bottom of the flange. Suspect this especially if the toilet is loose. You can test the integrity of the vent system by having someone on the roof apply a blow-dryer for hair set to NO heat to the vent on the roof. You can wet a hand and feel for bigger leaks. A candle flame or cigarette smoke will be blown away from any tiny leaks. Be aware that sewage gasses can explode so no flames if it smells strongly! The hair dryer should be sealed to the vent pipe with duct tape, that will be enough to contain the miniscule pressure created. Alternately you can do a 'sniff test' before you otherwise recognize the returning problem. Sooner or later you're bound to find the odor just as it begins and can narrow it down from there. If it's coming from the plumbing closet leave the door open for several minutes before sniff-testing so the odor will localize instead of filling the area. For more hard-to-reach areas use some plastic tubing that fits into a nostril and detect with the other end. Your helper may begin calling you 'Snuffleupagus' when they quit laughing; if that happens you hand them the tubing and tell them to guess what their new job is going to be. Works everytime!


Re: Sewage Smell in Basement

Thank you, for the reply.

I have checked the toilet and traps. They seem to be fine.

Checking the vent on the roof will have to wait until spring. Too much snow here in Massachusetts to go up on a 12 x12 pitch roof and I just had shoulder surgery last week (stupidly tried snowboarding!). Maybe I would be better off cutting the vent pipe in the attic and testing it from there?

Re: Sewage Smell in Basement

I would say I agree with the above posts. Looks like a bad Diy job. Get a home inspector to go over it with you if a plumber can't help. It does not look like it is even in code. Were permits obtained when this was added in the basement?

Daniel Farrell
Re: Sewage Smell in Basement

What if you don't smell it in the house just outside?

Re: Sewage Smell in Basement

This job was done by a Licensed Plumber here in Andover MA. The plumbing is in an addition that was built by a very reputable builder in the area. All inspections were done and signed off as well. Guess that does not say much for the quality of licensed work here.

However, I finally found the problem! Hidden behind the insulation in the closet was a vent pipe that they had never tied into the system. A picture has been attached. The yellow cap I had installed until I have time to get the materials to repair it.

Two licensed plumbers have had their heads in this closet looking for the problem. The only thing that both did was seal the effluent tank and give me a bill for the service call and time (approx. $200 per visit times two).

The question is: How could such an obvious thing be overlooked by the original plumber and inspector? This was easily seen prior to the install of the insulation and he installed it.

Re: Sewage Smell in Basement

This missed inspection item would never occur arond here in Palo Alto CA. To pass DWV inspection, the entire system must be filled with water with garden hose filling from roof. This can be scarey to do, if you have never done this before for a multi-story home. The pressure in basement can get quite high with 30 feet of water above. You need to make all plugs are reinforced. If any of these blow, you have a lot of water to clean up. But very rewarding when you pull the plug out at the street to drain the system.

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