Assess the specific situation Locate the influenced drain and extent of backup Check out if several drains are afflicted (suggests primary line difficulty) Seek out visible drinking water damage or overflow Primary DIY Methods Pour boiling water down drain Use plunger appropriate for sink/bathroom Attempt baking soda + vinegar Option https://www.kawatan.net/why-you-should-never-use-baking-soda-and-vinegar-to-unclog-a-drain/