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Sewer Odors

Contact Information: 

General Water and Sewer Questions: 303-280-7803

Water and Sewer Emergency 24-hour Hotline: 303-451-1289

Sewer Odors

What Causes the Odor?

Wastewater contains various dissolved gases. One of these gases is hydrogen sulfide, which smells like rotten eggs and is very noticeable in even small amounts. Since it is heavier than air, you may notice the odor more in the lower levels of the home. Hydrogen sulfide gas is toxic, so you'll want to address the problem immediately and preferably take preventive measures before you notice it.

You'll find curved pipes, called p-traps, in your plumbing system. Their purpose is to collect water, which prevents odors from backing up into the house. The water acts as an air-tight seal, so if you have a floor drain, sink, toilet, or shower that's not used regularly, the water may have evaporated, allowing odors to permeate your home.

Corroded pipes may also allow sewer gases to leak through.

Another cause may be a blocked vent located on your roof. Common blockages are the result of accumulated leaves or a bird's nest. If sewer gas cannot escape via this route, it will back up into your home.

How Do I Prevent It?

The easiest remedy for p-traps is to routinely (once per month) pour a gallon of water into these drains to ensure the trap adequately seals against the backup of gases. Some find it helpful to add ½ to 1 cup of bleach per gallon of water.

If you have fixtures absent of traps, or rusted/corroded pipes, call a plumber to correct the problem.

If it's a roof vent problem, a plumber may also be your best resource to handle the problem.

How Serious is It?

These odors should not be ignored. If the odor is strong, you should evacuate the building and call for assistance from a neighbor's home. The 24-hour line is 303-451-1289 for assistance, or you may also call the fire department. They have special gas detectors to measure the level of hydrogen sulfide, carbon dioxide and other gases in your home.