Assess your situation Track down the affected drain and extent of backup Check if many drains are affected (suggests primary line difficulty) Seek out obvious water problems or overflow Fundamental Do-it-yourself Steps Pour boiling drinking water down drain Use plunger suitable for sink/rest room Try out baking soda + vinegar https://www.kawatan.net/why-you-should-never-use-baking-soda-and-vinegar-to-unclog-a-drain/