Sewer Gas From My Kitchen Sink: Why?

Sewer gas smell emitting from a kitchen sink is unpleasant and can indicate safety issues.

Sewer gas has a very distinct and unpleasant odor, composed of ammonia, methane, carbon dioxide, hydrogen sulfide and sulfur dioxide. There are a couple of reasons sewer gas odor could be coming from your kitchen sink.

Traps

Commonly, sewer gas enters the house because a drain has not been used in awhile. When the water in the U-shaped "trap" below the drain dries out, it allows air from the sewer system to make its way past the trap, through the drain, and back up into the house. The simple solution is to run the water.

Cold Weather

Another reason sewer gas can enter the home is if the vent stack on the roof freezes shut. If there have been a few days of cold weather, this could be the culprit. To fix a vent stack, you can knock off the ice cap covering it or pour some hot water into the stack if the plug is internal.

Hidden Problems

Other blockages or problems with the plumbing, including hard-to-access areas behind walls, may mean hiring a professional to detect and fix the problem. Symptoms of sewer gas exposure include headache, nausea, dizziness or drowsiness, and in very high concentrations sewer gas could explode.

References

• Wisconsin Department of Health Services: Sewer Gas
• Ball State University: Indoor Environment Notebook
• Mother Earth News: That Lovely Sewer Gas Smell