Sewer Gas: The Reason for Bad Odor in the Bathrooms

Bad odors and scents are commonplace in bathrooms, basements, and other secluded areas, but when they’re permeating the house, it’s already a problem. A regular bad scent should waft away with proper ventilation. However, if it recurs regularly, then the inspection of a skilled plumber will be necessary.

More often than not, that nauseating sewer-like odor that you might notice is exactly sewer gas. This foul-smelling gas naturally occurs underneath your home due to the decomposition of waste materials within your sewer and septic systems. Noticing this smell inside your home is a problem that has to be attended to by a licensed plumber immediately, as this means several issues in your drain and sewer systems.

In this article, we will share with you four reasons sewer gas is spreading throughout your home:

1. Dry Water Traps in Floor Drains

Floor drains are fairly common in certain areas of your house, such as your bathroom, kitchen, laundry room, or basement. These drains are often contingencies for flooding, so you may not think of them too much. When the water that traps underneath the grate gets dry, however, sewer gas tends to flow into your house, so pouring in some water regularly can help.

If that doesn’t do the trick, then chances are that the cleanout plug of the trap is either gone or has eroded. Without a properly functioning plug, sewer gas is free to enter your home, making it very problematic for you.

2. Improper Sealing of the Toilet Flange

The toilet flange—where your toilet’s base connects to the floor—has to be properly sealed in so that gas won’t come out. If the wax ring seal wasn’t properly lain out, then sewer gas has a path into your bathroom.

Although this should not be a problem, improper toilet installation can indirectly be blamed for this, as it would allow toilets to rock, loosening the wax seal. Repairs for this require the removal of the toilet itself, so the assistance of a professional plumber will be needed.

3. Poor Ventilation

Your bathrooms, laundry rooms, and basements should have proper ventilation for any odors to clear out easily. Although ventilation is not the permanent answer to leaking sewer gas, this would allow you time to clean up and have the leaks repaired without it permanently ruining the atmosphere of your home.

4. Cracked Sewer Line

If a sewer line has a leak, then there will surely be foul-smelling sewer gas all over your residence. This can become even worse if it’s one of the sewer lines within your own home. If there is no immediate trace, call a professional plumber immediately to ensure no permanent damage happens to your home.


Foul odors around your house can be the prelude to a bigger house repair. Taking note of simple house maintenance tips and checking in regularly on points of concern will allow you to be on top of the situation. When you notice any of the tell-tale signs of sewer gas, then call a licensed plumber immediately to help you with repairs.

Are you looking for a professional plumber in San Diego? At PIC Plumbing Services, we are ready to take on any plumbing concerns or issues 24/7! Get in touch with us today and schedule an appointment!