Which of the following is classified as "black water"?

The classification of "black water" refers specifically to wastewater that contains fecal matter, urine, and other organic waste, making it a potential health hazard. Water from toilets is the primary source of black water because it directly carries human waste, which can include pathogens and other contaminants that pose risks to human health and the environment.

In contrast, the other options pertain to wastewater that is typically less contaminated. For instance, drainage from sinks, water from dishwashers, and water from showers are generally classified as "grey water." This type of water is used for household activities but does not contain significant amounts of pathogens as black water does. Additionally, grey water may still be reused for certain applications, such as irrigation, after appropriate treatment, whereas black water requires more stringent treatment and management due to its nature and potential risks.