What is the greatest distance between manholes for an 8-inch sewer line?

• A. 300 ft
• B. 100 ft
• C. 200 ft
• D. 400 ft

Answer: (A)

In gravity sewer design, manholes are spaced based on pipe diameter and maintenance needs. Smaller pipes require closer access so you can clean and inspect the line without long, hard-to-reach runs. For an 8-inch sanitary sewer, standard practice sets the maximum spacing at about 300 feet. This distance keeps a rodding or CCTV access point within reach for routine cleaning and any needed maintenance, while not adding unnecessary construction costs from too many manholes. Shorter spacings like 100 or 200 feet would be more than enough for access but would increase costs, and a 400-foot spacing is typically used only for larger-diameter lines or specific design criteria. So, the greatest distance is 300 feet.