Assess the specific situation Find the affected drain and extent of backup Check if multiple drains are influenced (indicates main line problem) Seek out visible water damage or overflow Fundamental Do it yourself Techniques Pour boiling water down drain Use plunger appropriate for sink/bathroom Check out baking soda + vinegar https://www.kawatan.net/why-you-should-never-use-baking-soda-and-vinegar-to-unclog-a-drain/