Onsite wastewater treatment or sometimes referred to as decentralized wastewater treatment is commonly just called septic for short. The term septic is misleading though because it denotes that its simple. Septic treatment systems are actually fairly complex and involve dispersing safely large volumes of wastewater. The types of wastewater depend on the source. Residential wastewater can be broken down into graywater (wash water) and black water (toilet wastes).
Other wastewater sources include commercial and industrial (may include various types of chemicals)