What is one key purpose of the septic tank?

The septic tank serves a vital function in the management of household wastewater by storing it before it is gradually released into the leach field. This storage process allows for the separation of solids from liquids, facilitating a settling process where heavier solids sink to the bottom, forming sludge, while lighter materials, such as grease, float to the top, forming scum. This stratification helps to ensure that the leach field only receives partially treated liquid, allowing for further biological treatment as the effluent percolates through the soil. Thus, the primary role of the septic tank is to provide a temporary holding space for wastewater, ensuring that it is released at a controlled rate to the subsequent systems designed to handle and treat the effluent.