Assess the Situation Identify the afflicted drain and extent of backup Test if a number of drains are affected (suggests principal line issue) Look for obvious water problems or overflow Basic Do-it-yourself Methods Pour boiling drinking water down drain Use plunger suitable for sink/toilet Try out baking soda + vinegar https://www.kawatan.net/why-you-should-never-use-baking-soda-and-vinegar-to-unclog-a-drain/