Which type of water is categorized as black water?

Black water is specifically classified as wastewater that contains human waste. This type of water poses significant health risks because it can contain pathogens and contaminants from bodily fluids, making it unsuitable for almost any use without proper treatment. The categorization of black water is primarily a public health concern, emphasizing the need for careful handling and treatment to prevent disease transmission.

In contrast, the other types of water listed, such as water from showers and sinks (often referred to as gray water), typically do not contain human waste and may be reused in certain applications (like irrigation) after some appropriate treatment. Water from washing machines also falls into the category of gray water and usually includes soap residues but lacks human waste. Stormwater runoff is primarily rainwater that collects pollutants like debris and chemicals on its way to drainage systems, but it does not contain human waste. Thus, the distinguishing factor that makes the correct answer black water is its direct association with human waste.