The small hole near your bathroom sink faucet, known as an overflow hole, serves a practical purpose that often goes unnoticed.

Its primary function is providing an alternate drainage route for rising water if the main sink drain is plugged or blocked.

While the opening helps prevent immediate bathroom flooding from a running tap, it has capacity limits and cannot fully stop heavy water flow.

Because the hidden channel behind the opening stays damp, it easily collects soap scum, skin oils, toothpaste, and general grime over time.

This enclosed, moist environment provides ideal conditions for mold and bacteria to grow, which often causes mysterious foul smells in the bathroom.

You can easily clean this hard-to-reach channel by using a simple combination of household baking soda and white vinegar.

Pouring baking soda followed by vinegar creates a bubbling chemical reaction that breaks down clung residue and lifts trapped grime.

Allow the mixture to sit inside the passage for five to ten minutes so the fizzing action can thoroughly neutralize odor-causing bacteria.

Rinse the channel thoroughly with warm water afterward to flush away the loosened debris directly into your sink’s main drainage pipe.

Regularly flushing and wiping this hidden opening keeps your sink fresh, free of odors, and functioning properly as an emergency backup.