What Causes a Sewer Smell From a Kitchen Sink?

Updated November 21, 2016

Your kitchen sink is an important food preparation tool. It is where you wash your dishes and provides a convenient place to toss vegetable peels or food wrappers until you have a chance to throw them out. A sewer smell coming from your kitchen sink can put all your cooking plans on hold until you get it fixed.

Sewer Smell

A sewer smell in a kitchen sink centres on the sink's drain. Sewer odours usually show up in sinks that go unused for weeks or months at a time, like those in a guest house or a vacation home. The odour will be strongest near the drain, but it spreads until the entire room smells unpleasant. The odour usually fades after the sink is used once or twice but returns as soon as activity in the kitchen ceases for another few weeks.


Your kitchen sink's drainpipe contains a curving section, shaped like the letter "U." This bending section is called a trap. When you run water into the sink, gravity causes some of it to remain inside the trap instead of continuing on into the sewer system. The water in the trap creates an airtight seal, preventing sewer gas and its odour from drifting back up the pipe and into your home. When a sink goes unused, the water in the trap can evaporate. Because no new water goes down the drain to replace it, the trap unseals, giving sewer gas an open path into your home.


Don't ignore the sewer smell in a sink. Sewer gas isn't just unpleasant to be around; it can also be dangerous. It contains hazardous gases, such as methane. If exposed to it, you or your family members could experience health problems such as headaches, nausea, vertigo and difficulty breathing. Exposure to high concentrations can cause you to lose consciousness. In large amounts, sewer gas can be a fire hazard. It can even explode.


Get rid of the sewer smell by opening windows. This helps dissipate the sewer gas in your home and reduces its danger to you. Next, run water from the faucet into the sink for 15 or 20 seconds. That's all it takes to refill the trap and seal of the drainpipe. Make pouring a few cups of water into the drain part of a biweekly maintenance schedule. If you will not return to the kitchen sink for longer than that, seal it off with a drain stopper. This blocks the sewer gas if the water in the trap evaporates.

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