How to Identify and Remove a Sewer Gas Smell in Your House

Possible Causes And Remedies To Rid Your House Of The Smell

corroded pipes

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Sewer gases backing up into your home can be a severe problem. "Sewer Gas" is a generic term for the noxious mix of chemicals that are the by-product of decaying waste. Sewer gas can include Hydrogen Sulfide, Ammonia, and Methane. Exposure to these gases can cause headaches, dizziness, memory loss, poisoning, and asphyxiation. In large enough amounts, there is even risk of fire or explosion.

Not all gas backups are so serious, and some are quite easily solved. How do you know if you have an urgent repair?

Common Causes

There are some pretty normal reasons why you may smell sewer gas in parts of your house that are easily fixed.

Water Traps

Water traps, sometimes called P-traps or S-traps are commonly located near floor drains and laundry tubs and are underneath every sink in the house. They work trapping water inside the curve and blocking the gas from traveling back into the house. If the trap is dried out, the sewer gas has a clear path into the house. If the smell is coming from a sink, simply run the water for a few seconds to restore the trap. If the smell is coming from a floor drain, pour a pitcher of water down the drain to restore the proper function. Traps dry out when they haven't been used much, the air in the house is very dry, or there is a leak somewhere before the trap.

Missing Clean-Out Plug

Check the drains for a clean-out plug. The clean-out plug caps the line that goes between your indoor system, and your outdoor system. At several points in your plumbing structure, clean-out lines are places for easy removal of clogs. The lines are capped so sewer gas cannot escape into the house. If one or more of these caps are missing or broken, this can be the culprit of the smell. You can buy a replacement plug at any hardware store.

Bad Wax Ring On The Toilet

In between the toilet flange and the base of the toilet, there should be a wax ring to provide a water and airtight seal. This wax ring can occasionally leak or become compromised, letting sewer gas into the home. If that's your cause, you'll need to replace the wax ring on the toilet.

It's Getting A Little More Serious

Other causes of the smell are not so simple and will require more extensive, more expensive repairs.

Sewer Or Septic Pipe Leaks

Sewer and septic line leaks are harder to diagnose and require more expertise to repair. If your toilet is gurgling and your drains are slow in addition to the sewer gas odor, you probably have a sewer line leak.

Loose Connections

Loose connections along the vent pipe or sewer line can also let the pungent gases into your home. These will most typically be inside of a wall or in the ceiling, so you'll appreciate the help of an experienced plumber to correct this issue.

Preventative Measures

While you can't do anything about roots going through sewer lines, or the wear and tear of time taking its toll on your systems, there are some steps to take to prevent the sewer gas issue from returning to your home.

Keep Water In All Of The Traps

Confirm the location of all of the plumbing traps in your home, whether they are in the floor, wall, under a sink or toilet, and make sure the least used traps keep their water level. For the traps that are seldom used and prone to drying out, you can pour a couple of tablespoons of vegetable oil on top of the water to help slow evaporation.

Clean Out Your Drains

It happens in every house - debris, hair, toys and all manner of particles can clog up the drains over time. To get them clean, remove the stopper, and clean the debris off of it. Set it aside. Bend a small hook at the end of a wire, stick it down the drain, pull out the debris and throw it in the trash. Repeat until you can't feel any more debris in the drain. Flush the drain with 4 to 5 gallons of boiling water and replace the stopper.

Keep The Vent Stack Free From Debris

The vent stack is the pipe that sticks out of your roof. Keep it free from clogs and debris. Use caution if your roof is steep or the stack is hard to reach.

Article Sources
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  1. Sewer Gas. Wisconsin Department of Health Services.

  2. Section 890.410 Fixture Traps/Continuous Waste. Illinois General Assembly Public Health.