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How an On-Site Wastewater Management System Works

On-site wastewater management systems are used to manage wastewater from households and holiday homes where no reticulated sewerage system is available. Although there are a great variety of systems currently available, all consist of two essential parts: the treatment unit and the land application area.

Treatment Unit

The treatment unit functions to separate the solids from the liquids and to breakdown organic matter within the wastewater. The most common form of treatment unit is the septic tank. Wastewater from the kitchen, toilet(s), bathroom(s) and laundry is directed into the septic tank. The heavier solids then settle at the bottom of the tank, while fats float to the top. The liquids then flow out of the tank.

With conventional on-site systems, the wastewater flows into the land application area, but in advanced on-site systems, the wastewater receives further treatment (such as aeration, filtration and disinfection) prior to being discharged.

Land Application Area

The wastewater from the treatment unit is discharged into the soil via trenches, beds, mounds or dripper lines. The area into which the wastewater is discharged is called the land application area. The wastewater still contains harmful bacteria and nutrients at this stage. Biological activity acts to provide essential further treatment as the wastewater passes through the soil.