Which of the following is considered a type of graywater?

Graywater is defined as wastewater that is generated from domestic activities such as laundry, dishwashing, and bathing, excluding any water that has come into contact with toilet waste. The key characteristic of graywater is that it can be reused for non-potable applications, which can significantly reduce water consumption and promote sustainable water management.

Option D correctly identifies graywater as wastewater that has not come into contact with toilet waste, making it suitable for recycling and reuse in applications such as irrigation and toilet flushing. This distinction is important in understanding water efficiency strategies, as graywater systems can help save potable water by utilizing this type of wastewater.

In contrast, water from kitchen sinks may contain food residues and grease, making it less suitable for many graywater applications, while wastewater from showers is generally considered graywater but would not apply if viewed through the scope of what defines graywater in the context of water efficiency systems.