What is the function of the septic tank?

The septic tank serves a crucial role in the wastewater management system. Its primary function is to filter solids from liquids and initiate the treatment process of wastewater generated from a household. When wastewater enters the septic tank, it separates into three layers: solids settle at the bottom, forming sludge; less dense materials such as fats and oils float to the top, creating a layer of scum; and the liquid effluent in the middle begins the initial stages of treatment through natural processes.

The design of the septic tank allows for anaerobic bacteria to break down the organic material in the sludge, thereby reducing the volume of waste and helping to treat the wastewater before it is discharged into the drain field for further filtration and absorption into the soil. This biological process is essential for the effective and safe disposal of household sewage.

In contrast, the other choices pertain to functions that are unrelated to the waste treatment process. The storage of household cleaning chemicals, collection of rainwater, and draining of excess water do not align with the septic tank's purpose or operation in wastewater management.