Septic tanks shall be rectangular in plan, cross-section and longitudinal view. The length to liquid depth to width ratio should be approximately equal or greater than 2 to 1 to 1 (2:1:1) and less than or equal to 3 to 1 to 1 (3:1:1). In no case shall the liquid depth be less than four feet or greater than eight feet.

Homeowners must have a permit from the local health department to construct, modify, or expand a septic system. The site must meet the standards in Virginia's Sewage Handling and Disposal Regulations before a construction permit is issued.

Anaerobic septic systems are popular among homeowners because they're more affordable. However, some homeowners prefer aerobic septic systems because they're more efficient. The price difference between the two is steep, with anaerobic systems ranging from $3,000–$8,000 and aerobic systems ranging from $10,000–$20,000.