<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=209258409501153&amp;ev=PageView&amp;noscript=1">
Green Builder Media Logo
Sign Up for  more articles like this

What's That Smell? Identifying (and Fixing) Sewer Odors Indoors

Posted by Robert Kravitz, Guest Columnist

Mar 7, 2017 7:57:00 AM

The most common way sewer odors get into buildings is through floor and fixture drains.

It's not just schools and commercial facilities that are impacted by what is typically known as sewer odors. Foul odors can also happen in homes, for similar reasons. This is an odor problem that can actually get worse when the system is used infequently. In homes, the culprit is often a floor drain in the basement or ground floor. In older homes, floor drains may tie in directly to mixed sewer lines, meaning they're in close proximity to raw, untreated waste, along with potential overflow from street sewers.


Dry Trap Blues. A slow leak or evaporation can cause the water level in the dry trap to sink, leaving room for foul air to come back up the pipe from sewer lines.

What causes sewer odors?
Sewer odors are the result of gases that contain such compounds as hydrogen sulfide, ammonia, carbon dioxide, methane, nitrogen, and hydrogen. 

Why do sewer odors smell so bad?
Hydrogen sulfide is usually the chief cause of the odors, along with ammonia.> 

How do sewer odor gases get inside a building?
The most common way these gases get into buildings is through dried out floor and fixture drains. The following are the most common routes: 

  • A blocked air vent. Every building should have an air vent system specifically for the plumbing in the building, This vent typically passes through all floors to exit from the roof.. If this venting is blocked at any point in its passage (or mistakenly cut off during remodeling!) odors can't be released outside and build up inside the building.
  • A damaged drain line. In some cases, the drain line may develop a crack or be broken. This can cause sewage to be released under or in the facility instead of being carried away, releasing odors.
  • A dry trap. This is the most common cause of sewer odors. A trap is the U-shaped pipe or tubing, which connects the drain to the sewer line. If the water held in the trap dries out, it releases odors into the building.

What should we do if we detect sewer odors in our building?

Take the easiest and least expensive steps first. If the odors are coming from a drain, pour about half a gallon of water down the drain and wait a day or two. If the odors dissipate, it indicates that the trap was dry.

However, this is a temporary fix. The trap will likely become dry again very soon. To address this, use a drain trap liquid to keep the trap filled for months, if not years. This will eliminate the odors associated with a dry trap.

If adding drain trap liquid does not solve the problem, cleaning the drain might help. This will remove bacteria, which may be causing the odor.

Finally, if sewer odors still persist, a plumber should be called in to investigate. A crack may have developed in the drain line, and this can be repaired only by a plumbing professional.

About the Author
Robert Kravitz represents Waterless Co. Inc., an innovative company that manufactures of no-water urinal systems. Based in Vista, CA, the 25-year-old company is the oldest manufacturer of waterless urinals in North America. 

© 2020, Green Builder Media. All rights reserved. This article is the exclusive property of Green Builder Media. If you would like to reprint this content, you are free to extract a short excerpt (no more than 1/4th of the total article), as long as you 1. credit the author, and 2. include a live link back to the original post on our site. Please contact a member of our editorial staff if you need more information.

Share This 

Connect with us on social media

facebook Instagram-logo1.gif twitter youtube linkedin pinterest 

New call-to-action
New call-to-action
New call-to-action