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Head to your local hardware, home improvement, or department store. There are 2 main types of drain pipes: galvanized metal and PVC. Older homes use the former, while modern homes have shifted to the latter. Be sure to check the kind of pipes your drain uses and select a product that is indicated for its use.  Hit your piping with a wrench—galvanized metal will ring, while PVC won't. In addition, PVC has copper crimp rings outside of the pipe holding its pieces together. If you have a septic tank, be sure to select a product that is labeled for use with these systems. Talk to a staff member and ask for product recommendations for your specific clog. Choose a product indicated for use with the clog type—tub, shower, sink, or toilet. Don't mix different kinds of chemicals. Keep the drain cleaner away from your eyes and skin. To be safe, wash your hands thoroughly with cool water. Pour a generous amount of baking soda to the surface of the sink, tub, and surrounding areas and remove it by scrubbing it thoroughly with a wet rag. Afterward, wipe any baking soda remnants with a paper towel.Place the drain cleaner somewhere out of reach if you have children.

Summary:
Find a drain cleaner that is intended for your system. Wash your hands and the area thoroughly after using any chemical drain cleaner.