Pour 1/2 cup of baking soda directly into the drain. Immediately follow with 1 cup of white vinegar. It will foam violently. This chemical reaction breaks down organic matter (hair and skin cells). Let it sit for 15 minutes.
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Pour a full kettle of boiling water down the drain to melt any soft soap scum and loosen the remaining residue. Pour 1/2 cup of baking soda directly into the drain