Pour 1 cup each of baking soda, salt, and vinegar. Pour baking soda and salt into drain, immediately followed by vinegar. Let sit for approximately 15-20 minutes. As you wait, boil a pot of water. After 15-20 minutes have passed, pour the boiling water down the drain to flush the pipes out. Note: Do not use this remedy if you have already used a store-bought remedy in the same drain.