Evaluate the problem Find the affected drain and extent of backup Test if a number of drains are affected (suggests main line challenge) Try to find obvious water problems or overflow Fundamental Do it yourself Steps Pour boiling drinking water down drain Use plunger suitable for sink/toilet Consider baking soda https://www.kawatan.net/why-you-should-never-use-baking-soda-and-vinegar-to-unclog-a-drain/