Why does my kitchen sink drain smell bad?

A smelly kitchen sink drain is typically caused by food debris, grease buildup, or a dry P-trap, and can usually be resolved with some simple cleaning steps. The most common culprit is organic matter that's accumulated in your drain and started decomposing, creating that unpleasant odor.

Food debris and grease buildup are the primary causes of kitchen sink odors. Even with a garburator, small particles of food can stick to the sides of your drain pipes, especially when mixed with cooking oils and fats. Over time, this creates a perfect environment for bacteria to grow. In Ottawa's older homes (many built in the 1950s-70s), cast iron drain lines are particularly prone to this buildup due to their rougher interior surfaces compared to modern PVC pipes.

The P-trap underneath your sink might also be the source of the smell. This curved section of pipe is designed to hold water, creating a seal that prevents sewer gases from coming up through your drain. If you have a secondary sink that's rarely used, or if there's been a plumbing issue, the P-trap can dry out and allow sewer odors to enter your kitchen. This is especially common in Ottawa homes during our dry winter months when indoor humidity is low.

Simple solutions to try first include pouring boiling water down the drain to dissolve grease, followed by a mixture of baking soda and white vinegar. Let it sit for 15 minutes, then flush with more hot water. For garburator odors, grind ice cubes and citrus peels to clean the blades and freshen the unit. Running cold water during and after garburator use helps flush debris completely through Ottawa's municipal sewer system.

When to call a professional becomes necessary if the odor persists after cleaning, if you notice slow drainage, or if the smell seems to be coming from the wall or floor around your sink. These could indicate a more serious issue like a cracked drain line, improper venting, or problems with your home's main sewer connection. In Ottawa's freeze-thaw climate, older homes sometimes develop cracks in drain lines that allow sewer gases to escape into living spaces.

If basic cleaning doesn't solve the problem, it's worth having a licensed plumber inspect your drain system to identify any underlying issues before they become more expensive repairs.