Greywater/WasteWater recycling; Graywater and blackwater are the two kinds of wastewater produced in all buildings and hospitality operations. Graywater comes from baths, sinks, showers and kitchens and can be recycled and reused for watering the garden or flushing toilets. Blackwater comes from toilets, and contains harmful pathogens. It must be properly treated before being discharged