Step One: Get the sitting water out of the sink or tub. This stage is crucial because otherwise the baking powder and vinegar solution will just mix into the grimy water. Use a cup or bucket to empty it if there is a lot.
Step Two: Remove the strainer or stopper. A strainer will have to be unscrewed and the grime washed clean. Some stoppers will simply twist out, while others require a screwdriver to unscrew the pivot rod. Stoppers collect a lot of hair, so make sure to clean the stopper thoroughly.
Step Three: Empty one-half cup of baking soda down the drain. Try and make sure all of the powder goes down. This may require a funnel depending on how available the drain opening is to you.
Step Four: Pour one-half cup of white vinegar down the drain. The vinegar will react with the baking soda making fizzing and popping foam. The foam has acidic properties that will eat away at whatever is clogging the drain.
Step Four: Cover the drain and let the mixture stand for five to ten minutes. The longer it is left in, the more it will eat away at the gunk, but don’t leave it so long that the mess has hardened up again before you do step five.
Step Five: Pour a pot of boiling water down the drain to rinse away the baking soda, vinegar, and loose debris. This will generally clear the drain; if not, repeat steps three through five until clear. Routinely applying this cleaning aid can help maintain a clear drain – you should use it once a month.
Step Six: Put stopper or strainer back in place. Twist the stopper back, or reattach the strainer with its screws.