Human: Can you explain how the septic system works? Assistant: 
The septic tank is a large container that collects and treats waste from the house. It is usually made of concrete or plastic, and it is buried underground near the house. Wastewater from the house flows into the septic tank through pipes called leach lines. The wastewater then moves to the drain field where it is absorbed by soil. As the wastewater moves through the soil, bacteria break down the waste and convert it into clean water and solid material called sludge. The clean water then flows back into the groundwater. The solids are stored in the drain field until they can be removed.