Which type of wastewater is relatively clean and comes from baths, sinks, and washing machines?

• A. Grey water
• B. Black water
• C. Stormwater
• D. Industrial wastewater

Answer: (A)

Greywater is the relatively clean wastewater that comes from baths, sinks, and washing machines. It originates from domestic fixtures that don’t include toilet waste, so it typically has fewer pathogens and pollutants than wastewater containing toilet waste. Because of this lower level of contamination, greywater can be treated with simple filtration and basic disinfection and reused for non-potable purposes like landscape irrigation or toilet flushing, helping to conserve fresh water. It isn’t safe to drink or cook with, and many places require a separate plumbing system or restrictions to prevent cross-connection with sewer lines. Other wastewater types differ: stormwater is rain runoff that can carry various pollutants and isn’t treated for reuse in the same way; industrial wastewater can contain chemicals and heavy metals; blackwater includes toilet waste and has a high pathogen load.