How to Identify and Remove Sewer Smell in Basement?

Basements are recognized for being among the home’s coldest and dampest areas. However, we don’t like talking about the sewer smell in basement areas. It’s not a good experience for many homeowners, mainly because we regularly utilize our cellars and basements.

Rather than risking health problems associated with these awful odors, put an end to them by learning how to get rid of basement stink on your own.

It saves you time and money by avoiding hiring an expert. Follow these helpful instructions if you’re ready to flush those horrible sewage gas scents down the toilet.

What is Sewer Gas?

sewer gas exit pipe

Sewer gas has a characteristic fetid, rotten egg odor to it. We’ve all smelled rotten eggs coming from a drain at some point. Hydrogen sulfide is the source of the “rotten egg” stench. A nasty sewer odor in the basement is not only unpleasant, but it can also be harmful [1].

The foul odor is caused by the decomposition of organic molecules, which releases gases such as hydrogen sulfide, ammonia, esters, carbon monoxide, and others. If you are exposed to the gases for an extended period, they might be harmful to your health. Some of these gases are even explosive.

Where does the sewer smell the basement come from?



  • Bacteria and Waste Decomposition

Decomposing garbage in the sewer system is the most typical cause of a sewer odor in your home. Sewage comprises a mixture of water, human waste, and food remnants, all of which have a foul odor when they decompose. Because the gases can be harmful, sewer systems are equipped with sewer traps to keep them from escaping.

In the system of residential toilets, there is a u-shaped sewage trap where water collects, producing a barrier preventing sewer gases from escaping into the house. However, if the trap is not correctly sealed with sewer plugs, or if the plugs have broken loose, sewer gas will inevitably escape, accompanied by a foul odor. [2]

  • Dried-Out Water Barrier

Suppose your house smells like a sewer during the rainy season. In that case, a possible explanation might be a dried-out water barrier in the sewage trap, which is usually caused by inactivity. The water barrier inside the sewer trap can dry out if you have a fixture in your home that isn’t used very often, such as a bathroom shower in the basement.

In addition, sewer smell in basement on hot days might also result from a dried-out water barrier. Running water from that fixture to refill the sewer trap and reestablish the water barrier is the most straightforward approach to remedy this.

Similarly, if a leak causes the u-shaped trap seal in your toilet to leak, sewage gases might escape and collect inside your home. Again, if not addressed quickly, this might harm your family’s health and well-being.

  •  Water and Pressure

When it rains, rainwater runoff must find somewhere to go. Due to gravity, the runoff will flow to the lowest location, which might be the sewage system or a septic tank with fractures. The gas is moved upward as the water gathers and takes up space. Because the gases have a lower density than water, they will leak into the building’s sewers, causing a foul odor.

Problems in the septic tank

septic tank outlet filter

If you there is a sewer smell in basement after rain, it could be the result of a combination of the following factors:

  • Rain frequently produces fluctuations in atmospheric pressure, which can cause the air to become heavy. As a result, the methane gas found in septic tanks does not flow down the vent as freely as it should. Instead, it clings to the ground, emitting a horrible odor.
  • Plumbing vent stacks can experience downdrafts due to cold temperatures. The stench will change throughout the day in this situation, especially if the weather is breezy. Downdrafts are to blame for the horrible sewage stench in your house if the odor tends to lessen as the temperature rises.
  • If the septic tank is full, it can cause the pump to malfunction. As a result, no new wastewater will flow in to replace the old sewage, resulting in a foul odor.
  • A clogged septic tank venting system could also cause a sewage odor in your home. If you’ve had work done on your home or landscaping, and the vents aren’t operating correctly, this is a common occurrence. As a result, sewage gases that cannot escape the sewers will build up in your home, generating a terrible odor.

 Other Causes of a Sewer Smell in Your Home

  • Cracked pipes: Degraded, broken, or burst tubes can allow sewer gas to flow through them and into your home, causing a sewer odor.
  • Leaks: Incorrectly installed pipes or vents in your plumbing system can result in leakages, allowing sewer gas to enter your home. Similarly, if the ducts are too close to a window or an air intake, sewage gas can escape into your home. In addition, leaks from neighboring septic systems might infiltrate your property through foundation gaps in some situations.
  • Blocked drains: Drains are in charge of transporting hazardous waste via the septic system. Sewage backup produced by objects that shouldn’t have been flushed into the system is the most prevalent cause of clogged drains. If you do not remove the blockage is not removed, it will continue to decay and emit a foul odor in your home.
  • Loose toilets: Toilets that aren’t tightly connected to sewer lines might leak gas into your home.

Is the sewer smell in basement dangerous? 

Yes, breathing sewer gas can be harmful to your health.

Sewer gas comprises hydrogen sulfide, methane, ammonia, and carbon dioxide, among other gases. While sewer gas isn’t harmful in tiny amounts, a significant concentration can quickly lead to substantial toxicity levels.

Studies have demonstrated that hydrogen sulfide is hazardous to human and animal circulatory systems. In addition, high levels of hydrogen sulfide can cause severe symptoms, including organ failure and even death. [3]

Ammonia is a chemical component that is commonly used in cleaning products. It’s noted for having a distinct odor. Low-level ammonia exposure can irritate the eyes, nose, and throat. The chemical can cause organ damage or death at higher concentrations.

Humans are relatively unaffected by both methane and carbon dioxide. Methane, on the other hand, is exceedingly explosive in large quantities. Given that ammonia is also highly flammable, sewage gas can pose a significant fire threat at greater concentrations.

How to eliminate sewer smell in basement


  1. Identify the source of the smell

The majority of efforts to determine the source of sewer gas smell in your home rely on trial and error methods. First, you must understand what causes sewer gas to leak into your home and where to search beyond a septic tank leak.

It is good to start with the drains, vents, and pipes themselves when it comes to plumbing issues. So when looking for sewage leaks and problems, have some of this equipment on hand.

Washing machines in the basement is another major source of problems. You should also rule out any other potential issues, such as mold and mildew.

Molds cause many of the same medical problems as bacteria, such as respiratory problems and allergic reactions. Treat tiny areas with bleach if you feel mold is to blame. Otherwise, if you have an infestation, you should contact a specialist.

  1. Fix the dried out water trap

A dried-up water trap is one of the most common reasons for a sewer smell in your basement. The water trap is situated inside drains on the basement floor and safeguards the room from flooding. These traps regularly store a small amount of water to plug the pipeline and keep the unpleasant stench from ruining your basement.

However, in cases where the water trap is not used for long, it will dry out and lose its ability to keep odors away. On warmer days, the evaporation of the water in the tramp, leaving it dry, can cause a sewer odor in the basement. Fortunately, all it takes is a little hot water to fix the problem.

Put approximately one gallon of water into the dry trap, along with a teaspoon of mild dish detergent for a new aroma. This method also works to eliminate sewer odors from shower drains.

  1. Check and fix the cleanout plug.

Another common source of sewage odor in your floor drain is a defective cleanout plug. Rather than collecting sewage water inside the drain, the plug directs it down into the sewage line. Unfortunately, nothing can stop sewage gas from leaking back into your home if the plug is damaged or fractures due to regular wear and tear.

Replacing the cleanout component is the most straightforward remedy. To begin, remove the drain grate to inspect its condition. If it’s cracked or completely missing, go to the store and get a new one. Otherwise, look for other sources of foul odor.

  1. Ensure proper ventilation is maintained

Most sewer systems have vents system that guides the flow of sewer gases out of the house. However, if you have a laundry machine whose drain is clogged or not connected correctly, the foul odors will flow back into your home. The best approach to handle the issue is to inspect the pipes and use bleach to clean any obstructions.

Air conditioners, for example, may have an inadequately connected HVAC system to a sewage vent pipe, resulting in improper ventilation. Fixtures could also cause it in other parts of the house that are either close by or have pipes that link somewhere in the basement.

For example, a damaged p-trap on a toilet or kitchen sink may cause the sewer gas to be released into the air instead of trapping it in the pipes as intended. A faulty toilet flange or wax ring can also cause a slew of issues.

It’s essential that you replace the seal when it gets broken. Consider also replacing the caulk around the toilet’s base as soon as it gets dry and cracked.

  1. Fix or replace damaged sewer lines

A damaged ejector pit or destruction to the piping itself are just a few of the problems with sewer lines that can generate these foul odors. A tight seal is required on the ejector pit to keep the gas out, so inspect it for cracks and damage.

Cracks in the pipes are another issue. The effluent from the sewage system seeps into the ground and the sump pump. Your basement is kept dry by this sump pump.

If your pump accumulates too much sewer water, the stench will seep into your home. To prevent more harm, you will need professional assistance from a plumber to resolve this issue.

  1. Get rid of odor in the water heater.

Your water heater could be the source of foul basement odors. Anaerobic bacteria also produce the same sulfur odor produced by a clogged sewage drain. Most of the time, treating this issue on your own is simple and only involves a hydrogen peroxide little patience.

To begin, turn off the cold water faucet and remove part of the water from the heating system. Next, disconnect the metal line and fill the container with hydrogen peroxide using a funnel.

For every 10 gallons of water in the unit, add one cup of hydrogen peroxide. Reconnect the hose and turn on the cold water valve. Allow the tank to fill up and settle for several hours before restarting the engine.

  1. Prevent Drain Clogs with Vinegar

Vinegar clears obstructions in drain lines and maintains the septic system in perfect working order. If you notice a foul odor or water emptying too slowly in sinks, showers, or the toilet, use this basement smell eliminator with the explosive combination of vinegar and baking soda.

First, pour the baking soda down the drainpipe. Next, pour vinegar into the drain and allow the two substances to react.

Unscrew the plug and pour hot water down the drain after allowing this mixture to settle for around 30 minutes.

Keep your house free of sewer smell.

It’s crucial that you take swift action if you notice a sewer odor in your basement to reduce the amount of exposure to folks within your home. The implications of even a modest amount of hydrogen sulfide on your family’s health can be disastrous.

First, keep your house and those who live in it from these negative consequences. Then, you can hire a plumber to develop a suitable solution for your family.