A septic system processes and purifies household and commercial waste (effluent). A standard septic system is typically installed on-site and has two components: a septic tank and a leachfield or drainfield. The effluent consists of blackwater (toilet wastes) and graywater (kitchen sink, bathtub and laundry wastes). Primary treatment occurs in the septic tank, where helpful bacteria digest organic matter in the wastewater. The effluent then flows into the leachfield for secondary treatment. Here, bacteria complete the digestion and purification process as the wastewater slowly leaches into the soil.