Evaluate your situation Identify the influenced drain and extent of backup Look at if many drains are influenced (indicates key line concern) Hunt for obvious water injury or overflow Primary DIY Measures Pour boiling drinking water down drain Use plunger appropriate for sink/rest room Attempt baking soda + vinegar Option https://www.kawatan.net/why-you-should-never-use-baking-soda-and-vinegar-to-unclog-a-drain/