Septic system

A septic system treats household wastewater on the property where it is produced. It separates solids in a tank and disperses partially treated effluent into soil for further treatment.

Septic tank: A buried watertight tank that settles solids and allows anaerobic breakdown of household wastewater. It is the system’s first treatment stage, separating sludge and scum before effluent leaves the tank.
Wastewater: Water contaminated by household, commercial, or industrial use. A septic system treats the wastewater generated by a property rather than sending it to a central plant.
Onsite wastewater treatment: The treatment and disposal of wastewater at or near the property where it is generated. A septic system is a common form of onsite wastewater treatment for homes beyond sewer networks.
Fecal indicator bacteria: Microorganisms used to indicate possible contamination by fecal waste in water. Their presence in nearby water can signal that septic treatment or containment is failing.
Drain field: A network of perforated pipes or trenches that distributes septic effluent into soil. It spreads tank effluent through soil, where filtration and microbial activity provide further treatment.
Primary treatment: The physical separation of settleable and floating solids from wastewater. Settling and scum formation in the septic tank perform a form of primary treatment.
Septic tank pumping: The removal of accumulated sludge and scum from a septic tank by a vacuum truck. Periodic pumping prevents solids from escaping the tank and damaging the dispersal area.
Nitrate contamination: The presence of elevated nitrate in water, often from fertilizers, sewage, or animal waste. Nitrogen from septic effluent can travel through soil and raise nitrate levels in groundwater.
Soil absorption system: An engineered soil area that receives wastewater effluent and filters or biologically treats it. Its soil provides the final treatment and dispersal stage of a conventional septic system.
Biochemical oxygen demand: A measure of the oxygen microorganisms need to break down biodegradable material in water. Organic matter in septic effluent can consume oxygen as soil microbes continue treatment.

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