Removing Basement odors and smells

Removing Basement Odors and Smells

Removing basement odors and smells: these odors are usually caused by methane gas, a common problem for finished basements, frequently from drain pipes, sump pumps and sewers. Eliminating basement odors can be an easy do-it-yourself project.

A common complaint from those people who have homes with finished basements is that they often smell sewer gases. This is particularly true when they run an appliance such as a washing machine or dishwasher.

Often, the odor makes it way through the house and can be smelled upstairs.
Such a home environment problem may actually have a simple solution, say plumbing experts. It is highly likely that those odors are coming from the floors drains in your basement.

Methane Gas

Because this is a methane gas, it’s probably more of a nuisance than any sort of danger, like radon gas can pose (on that note, it wouldn’t be a bad idea to purchase a radon gas detector kit if you have living space in your basement).

Here what probably causes the problem: Below each floor drain is a U-shaped or elbow pipe, the same type of pipe that’s found under your kitchen and bathroom sinks.
The purpose of this pipe is to trap a bit of water in that U-shaped bend. That water acts as a plug, preventing sewer gases from coming back up the pipe and through the drain into a home.

Instead, the sewer gases go up a vertical vent pipe that exits your home through the roof. Now when someone runs washing machine, it can discharge water into a sump pump or ejector pump and into an ejector pit. The discharge pipe from a basement bathroom and probably the floor drains are also sometimes connected to that sump or ejector pit.

In some cases, trapped odors or smells can come from other sources. It may take some looking and investigating, but you should eventually find the cause.

When a washing machine discharge fills up the pit, it probably pushes the air in that pit up through the floor drains, bringing up the odors of that pit with it.
That smell can easily be spread throughout the rest of the house if you have a forced-air heating and air conditioning system. The system’s blower motor picks up that odor and pumps it through a home’s ductwork.

Simple Solutions to some smelly issues

What is the simple solution? Fill the floor drains with a half gallon or so of water. That will create the water plug needed to keep those sewer gases out of the basement.
And don’t let them dry out. Hopefully, that will clear up any drain smells. If it doesn’t, then it’s probably worthwhile to try something called a plumber’s peppermint test. That consists of placing oil of peppermint into the plumbing system to see how smells are being carried by those pipes through the house.

Mold and Mildew

Another possible source of basement odors is mold and mildew. This is the result of basement flooding or regular seepage. In addition to an odor or stuffy, stale air, mold and mildew can cause such problems as itchy throats and irritated eyes. They can also bother people with allergies and mold especially can be a key trigger for asthma. Mold can also create a weakness in the structure of a home by attacking wood.

If you find visible mold or mildew in a basement, use a diluted bleach solution to clean it. If you can’t clean a carpet or piece of furniture that has been water damaged within 24 hours, consider replacing it.

To alleviate mold and mildew, make sure water – rainwater – isn’t getting into your basement. Correct seepage problems in basements or crawlspaces and repair any leaks in the roof or siding. Fix gutters that may be contributing to the problem. If there is minor seepage, one low-cost solution is to patch any cracks and holes from the inside with hydraulic cement, a quick-setting mixture that expands when it reaches water. Another low-cost solution is waterproofing paint made especially for basements. Both are available at home improvement stores. The cement usually costs about $20 while the paint, depending on the brand, can cost several hundred dollars to cover all the floors and walls of a large basement.

Muggy Feeling and Odors

Another simple way to take the muggy feeling and odor out of a basement is to purchase a dehumidifier. The devices come in a wide range of shape and sizes and resemble portable room humidifiers.

Removing Basement Odors and Smells


Dehumidifiers eliminate excess moisture from a room by drawing air over the refrigerated coils. The moisture in the air condenses into water and is collected in a tank. The water can also be routed automatically to a drain.
© by Jim Sulski