Sewer Gas Smell

sewer gas smell

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How to Detect and Get Rid of a Sewer Gas Smell in Your House

Sewer gases re-entering your home can be a terrible issue. The term sewer gas refers to the by-products of decomposing waste which results in a toxic mix of chemicals.

If your home suddenly smells like rotten eggs then you have a sewer gas issue. Not every gas backup is severe, and some can be resolved quite easily.

Here’s how to know if you require an urgent fix.

Common Reasons for Sewer Gas Smells

There are some very regular reasons why sewer gas may smell in some areas of your home which can be easily fixed.

Water Traps

Sometimes referred to as S-traps or P-traps, water traps are typically positioned close to laundry tubs and floor drains, and also under every home sink.

They trap water inside their curves and block these gases from backing up into the home.

Traps can dry out when there is very dry air in the house, there is a leakage somewhere before the trap, or they have not been used often.

With a dried trap, sewer gas can more easily enter the house.

These smells can come from either the sink or floor drain and can be easily solved by running water down the drains for a little while to restore the trap function.

Absent Clean-Out Plug

Clean-out plugs are the main sewer access points, normally located at the walls of the foundation.

Through them, the line can be snaked out to stop gases from backing up into your home.

Check them for the house traps or any mainline trap. Clogs can be removed easily from clean-out lines, and they are such that stop sewer gases.

You may experience this smell if one or even more of these caps get broken or missing.

Replacement plugs are available at any hardware shop.

Damaged Toilet Wax Ring

A wax ring is located between the toilet base and toilet flange and provides an airtight and watertight seal.

Sometimes, this wax ring may leak or get compromised and allow sewer gas in. If you are experiencing this, you’ll have to replace your toilet wax ring.

Septic Pipe or Sewer Leaks

Leaks along the septic line and sewer are very difficult to detect and repairs require more expertise.

If you are having a gurgling toilet and slow drains as well as the sewer gas smell, your sewer line likely has a leak.

Loose Connections

The sewer line or vent pipe may have loose connections that can serve as an entry point for sewer gas into your home. Usually, these can be found in the ceiling or inside a wall so you may require a skilled plumber to fix them.

Preventive Routines

Though there may be nothing you can do about wear and tear on your plumbing connections over time or even roots passing through your sewer lines, you may still be able to stop sewer gas from backing up into your house with a few steps.

Ensure All Traps Have Water

Confirm where all of your home’s plumbing traps are located (either in the wall, floor, or under a toilet or sink), and be sure to retain water even in the least used of them.

For those that are rarely used and likely dry out, pour a few tablespoons of vegetable oil on the water in order to slow down evaporation.

Clear Your Drains

Every house has debris, toys, hair, and all sorts of particles going in the drains that can accumulate over time and cause blocked drains.

Simply take out the stopper and remove the debris from the drains.

Use a wire with a hook at the end to stick into the drain and take out any debris until there is none left.

Use between 4 and 5 gallons of very hot water (not boiling water) to flush the drains and then reposition the stopper.


The wire won’t be as long as the drain line. If a small drain snake or wire cannot clear the drain line properly, then you may have to get professional help.

Ensure there is No Debris in the Vent Stack

The pipe sticking out of the roof of your house is known as the vent stack. Make sure it is free from debris and clogs.

Clearing the vent stack should not be a frequent exercise unless you have trees whose branches hang right over it.

If this is the case, you need to get a professional to clear it.

Is Sewer Gas Harmful?

Ammonia, methane, and hydrogen sulfide (responsible for its characteristic rotten eggs odor) are contained in sewer gas smell.

Exposure to a high concentration of sewer gas in homes is quite rare, unlike in an industrial environment.

A high concentration of sewer gases may lead to certain symptoms such as headaches, nausea or vomiting, dizziness, memory loss, asphyxiation, and poisoning.

There is a risk of explosion or fire when these gases are in far larger amounts.

If you are having a hard time detecting the problem, get a plumber immediately to check your home.

Then properly air out your house and move outside to get some fresh air. Hydrogen sulfide in lower levels will be naturally and quickly excreted from your body through fluids.

Call us at (559) 940-0890

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