Which of the following is NOT a component of a septic system?

A septic system typically consists of several essential components that work together to treat and dispose of wastewater effectively. The septic tank serves as the initial treatment unit, where solids settle to the bottom while lighter materials, such as grease, float to the top, forming a scum layer. The drain field, also known as a leach field, is critical for dispersing and further treating the effluent that flows from the septic tank into the soil, allowing natural filtration and absorption into the groundwater.

A pump station may also be integrated into a septic system to aid in the movement of wastewater when gravity flow is insufficient, often found in systems where the terrain is not conducive to natural drainage.

In contrast, a composting unit serves a different purpose and is not considered a standard component of a traditional septic system. Composting units are designed for the processing of organic waste, often found in composting toilets, and utilize aerobic processes to break down human waste and other organic materials into compost, rather than being part of a wastewater treatment and disposal method like a septic system. Thus, this distinguishes it clearly from the other components, reinforcing that a composting unit is not part of a septic system.