This "volcano" reaction helps loosen gunk and neutralize smells.

: Follow with 1/2 cup of white distilled vinegar.

: Pour 1/2 cup of baking soda directly into the drain.

How to unclog a drain without harsh chemicals - David Suzuki Foundation

If your sink is full of standing water, bail it out with a cup. For this method to work, the drain needs to be clear of standing water so the baking soda can go directly into the pipe.

Chemical drain cleaners are effective, but they come with risks. They can damage old pipes, burn your skin, and release harmful fumes into your home. Baking soda (sodium bicarbonate) offers a safer alternative that is:

: Immediately cover the drain with a plug or wet cloth for 10 to 30 minutes to force the fizzing reaction downward.

Pour directly down the drain. Use a funnel if the opening is small to ensure the powder goes down the pipe rather than sitting in the sink basin.