For underground piping greater than 2 inches in diameter, what is the maximum developed length between cleanouts?

• A. 75'
• B. 60'
• C. 90'
• D. 120'

Answer: (A)

Access to a drainage line for cleaning is the key idea. Cleanouts must be placed so a snake or other cleaning tool can reach from one access point to the next without having to dig up more pipe. For underground piping larger than 2 inches in diameter, the standard rule is that the developed length between cleanouts should not exceed 75 feet. This maintains a practical reach for typical cleaning equipment and ensures blockages can be cleared from a cleanout without excessive effort or additional access points. If the run were longer, such as 90 or 120 feet, a cleanout at one end wouldn’t reliably allow a tool to reach the other end. A smaller-pipe rule (often about 60 feet) exists in some codes, but the question focuses on oversized underground piping, where 75 feet is the limit. The distance is measured along the pipe's length between cleanouts, accounting for the actual straight runs and fittings that define that distance.