Let the mixture work. For tough clogs (e.g., hair and soap), wait 30 minutes or even overnight. You’ll hear occasional fizzing.
Slowly pour the boiling water directly into the drain to soften and loosen grease, soap scum, and debris.
Bring 2–4 cups of water to a rolling boil.
Immediately pour 1 cup of white vinegar down the drain. You’ll hear fizzing and bubbling – that’s the chemical reaction breaking down organic matter.
Remove the cover. Boil another 2–4 cups of water (or run the hottest tap water for 1–2 minutes) and flush the drain thoroughly.
Pour 1/2 cup of baking soda directly into the drain. Use a spoon or your finger to push any dry baking soda that sticks to the sides down the opening.