Evaluate your situation Track down the affected drain and extent of backup Check if a number of drains are affected (suggests primary line difficulty) Seek out obvious water destruction or overflow Simple Do it yourself Actions 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/