Liquid domestic, commercial, and industrial waste that includes sewage, storm water, and liquid industrial effluent. In some sewage disposal systems, no distinction is made, but in those in which surplus water or toxic effluent could inactivate the system, these varieties of wastewater must be segregated. Many cities with sewerage systems have separate drains for storm water for this reason, especially if the areas are subject to torrential rainstorms. Wastewater from public and domestic toilets is always polluted and is referred to as “black water.” Water from domestic baths, kitchens, laundries, etc., is nonpotable, but usually it may be used for irrigation. This is referred to as “gray water.”
Subjects: Public Health and Epidemiology.