What causes a musty smell in the kitchen sink drain?

Updated March 23, 2017

We associate a clean home with a fresh smell, so it can be frustrating to thoroughly clean the kitchen, only to realise there is still a musty smell emanating from the drain area. Fortunately, there's likely a simple cause and with several solutions. If you have a garbage disposal, sufficient water needs to run through it down into the drain to avoid odour-causing build-up.

Causes of Odor

Make sure the odour is coming from the drain. Look under the sink for any damp sponges or other items that could cause the smell. Once you've determined it is coming from the drain, the most likely culprit is decomposing organic debris. If you have a garbage disposal, you likely have put food down it. Run the water while you run the disposal motor to wash debris down the pipes.

Natural Remedies

Run water in the sink for at least 45 seconds. Put the stopper in the bottom of the sink and fill it with warm, soapy water. Once the sink is full, pull the stopper and allow the soapy water to go into the drain. If the smell is on the side of the garbage disposal, run the disposal for about 30 seconds. The disposal will act as an agitator to get the soapy water to food debris. Even if the smell is coming from a drain that does not have a disposal, go through the same process of filling the sink. While the sink is draining, turn on the water to give it more power. Next, sprinkle baking soda and vinegar down the drain. Let it sit for a few minutes and rinse. Or you can try concentrated lemon juice, which will not only help clear the drain, but will leave your sink smelling fresh.

Chemical Solution

Turn on the faucet on and fill the drain as quickly as possible. Turn the faucet off and put a half cup of powdered oxygen bleach down the drain. Millions of tiny oxygen ions will begin to soften anything that has hardened in your drain. Leave the solution in the drain for up to an hour, then rinse thoroughly.


It's important to allow water to rinse any food or debris down into the pipes. Many people only leave the water running for the few seconds while the disposal is operating, or just long enough to wash something out of the sink and down the drain. If you leave the water on for a bit longer, it will push debris and potential odour-causing build-up past the drain area.

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About the Author

Dana Sparks has been a professional writer since 1990. As a staff reporter, she has written hundreds of newspaper and magazine articles, and she is also the author of two published novels. Sparks holds a Bachelor of Arts in business.