pour about a half cup of baking soda down the drain, and then pour in vinegar until it bubbles up to the top of the drain. I leave that for about 15 minutes, and then pour really hot water (not quite to boiling) down the drain. This will help disinfect the drain and clean it too.
<3 UNCLOG DRAINS: Pour 1 cup of baking soda down the drain followed by 1 cup of vinegar. You can try heating the vinegar in the microwave for a few seconds before adding it to the drain. Wait 5 minutes before flushing the drain with 2 quarts of hot water~ I do this Monthly~