Septic system design involves creating a system that treats and disposes of wastewater from homes not connected to a public sewer. The system typically includes a septic tank that collects solids and allows liquids to flow into a drain field, where the wastewater is naturally filtered through soil. Key factors in septic system design include the size of the household, soil type, and local regulations. Proper design ensures effective treatment of wastewater, preventing contamination of groundwater and protecting public health. Regular maintenance, such as pumping the septic tank, is essential for optimal performance and longevity of the system.