The wastewater from the house goes into three septic tanks. After it is treated mechanically, it is drawn out of the septic tanks with a transportation mechanism into a biozone. This contains slowly rotating biodisks, on which a biomass of micro-organisms live. It is there that the actual treatment process takes place. The treated wastewater (the second class of purity) is released from the treatment tank through a tilted overflow. Purified and oxygenated, it flows into a small pond in which fish live and various waterplants grow.