What plumbing fixture is used for flushing human waste?

The plumbing fixture specifically designed for flushing human waste is the water closet. This term refers to what is commonly known as a toilet, which uses water to remove waste from the bowl through a trap and into the sewage system. The design of a water closet incorporates a flushing mechanism that allows for effective waste removal, ensuring proper sanitation and hygiene.

In comparison, while a bidet is a fixture used for cleaning the body after using the toilet, it does not flush human waste. Similarly, a sink is primarily for washing hands, dishes, and other items, and does not serve the purpose of waste removal. A urinal is intended for urination only and is designed differently from a water closet, as it does not accommodate human waste in the same comprehensive manner. Thus, the water closet is the definitive choice for the function of flushing human waste.