Pour about 1 gallon boiling water down your drain. This will break up and soften buildup.
Drop 1 cup baking soda down the drain, which will clean and deodorize it.
Add 1 cup of white vinegar to the drain, which disinfects plus combines with the baking soda to create a foaming action that breaks apart the residue and loosens buildup from the walls of the drain. Let the cleaning mixture work for about 1 hour.
Pour 1 gallon of hot water down the drain again for a final rinse and wash away all the loosened residue.
Repeat about once per month to keep clogging and odor to a minimum.