Removing Odors from a Basement


January 16, 2012

unfinished basementI have the smell of rotten onion in my basement, we can't find the source. Do you have any suggestions?

By Sherrie



Gold Post Medal for All Time! 969 Posts
January 17, 20120 found this helpful

I googled "rotten onion smell in basement" and got some really good articles, including one from here in 06. I hope that helps.

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January 18, 20120 found this helpful

Could this be an animal marking its territory, or nesting? I have cats, so don't have such issues. An animal in your case might even be a snake, since they may deposit odors. It is winter and animals seek the warmth of the indoors. I hope you figure out what it is. It seems like an animal must be the source.

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January 22, 20120 found this helpful

Check to see if you have any dry sink or bath tub drains. If you have a bathroom or wetbar sink that isn't used regularly, a dry trap can let sewer odors back into the home. Do you have a dry sump pump?


Same problem. Do you have any plants in water vases? If water is not changed regularly, roots begin to rot and stink. Are you storing any root vegetables that might be going bad?

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September 23, 20170 found this helpful

That could be a decomposition of a mouse or other animal .had that smell coming in my house when winter came and we put the heat on eeventually it must have dried out smell went away but it was around two weeks

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4 More Questions

Ask a QuestionHere are the questions asked by community members. Read on to see the answers provided by the ThriftyFun community or ask a new question.

February 26, 2017

We have had this horrific smell coming from the basement for about 5 days. It's working it way upstairs. We went through a storage area where the smell was coming from, but we didn't find anything dead. That's how bad this smell is. The smell is in the bi-fold door to the storage area, but we can't figure out what's causing it.

It's Saturday and I called a company that handles odors in the home, but they were closed. We do not have any gas in our home and my husband checked all the drains. Can you give any suggestions? Please?


Bronze Post Medal for All Time! 107 Posts
February 26, 20170 found this helpful

I am pretty certain that what you are experiencing is a dead animal. I have had this happen to me before, especially at times when i was putting out traps for rodents.


I once spent 2 days where all I did was look for the decaying corpse of something in our apartment. I did eventually find it, but it was not fun. It involved going in the attic, pulling apart a bunch of boxes, pulling the whole house away, etc

Most likely the thing died inside your walls, which is why you can't find it.

it could also be a sewage problem, but I think you would know what sewage v decomposing body smells like.

if it is a dead thing and you just can't find it, take heart: if it's a mouse, it should not last longer than a week. But if it's a bigger thing, you might be stuck with it for up to a month. The thing will smell until the animal has decomposed to the dry bones.

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Bronze Answer Medal for All Time! 138 Answers
March 3, 20170 found this helpful

it's caused by rain and the sewers outside your home-dead leaves and other garbage decompose and the smell has nowhere to go but up and out. try and get the neighbors not to rake leaves into the street

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June 10, 2010

How do I remove pet odor from a concrete basement floor?

By ann hr from Indianapolis, IN


June 10, 20100 found this helpful

Use the "Pee Recipe" - it's not just for pee.
2 c. peroxide
2 t. baking soda
2 small drops liquid dish detergent

Mix gently and then pour on area. Do not wipe up - let it dry on it's own, undisturbed, for however long it takes. The smells will be gone.


You can use this on dog, cat, human urine, feces, vomit. On carpet (test for colorfastness first in an inconspicuous area), mattresses, concrete, etc. Using a watering can (with sprinkler top) helps to distribute more evenly.

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July 14, 2013

My basement flooded. After the water drained it left a terrible odor. What can be used to remove the odor?

By Vivian T B.

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ThriftyFun is one of the longest running frugal living communities on the Internet. These are archives of older discussions.

June 10, 2010

My son is selling his house and the basement has a horrible dog odor from where the dogs were kept. Can anyone suggest a solution I can apply to neutralize the smell? The area has a concrete floor.

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