A septic system is an underground wastewater treatment structure, used in rural areas without centralized sewer systems. It consists of a septic tank and a drain field.

On average, a well-designed, properly installed, and diligently maintained septic system can last anywhere from 20 to 40 years. However, some systems have been known to function effectively for over 50 years with exceptional care and favorable conditions. The lifespan of a septic system is influenced by several factors, including the type of system, soil conditions, usage patterns, and maintenance practices.