Depending on the severity of the clog, vinegar and baking soda may be used to unclog a drain. Pour 1/2 cup of baking soda down the drain, and then follow it with 1/2 cup of vinegar. Replace the cover of the drain loosely to keep fumes and foam at bay.
After the vinegar and baking soda blend has been in the drain for three hours, run water form the faucet to clear it. For drains that are clogged due to grease, pour 1/2 cup of baking soda into the drain, and then pour in 1/2 cup of salt. Pour a kettle full of boiling water down the drain, and let it sit overnight.