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

• A. 20'
• B. 60'
• C. 40'
• D. 80'

Answer: (C)

Access to clear clogs relies on cleanouts being placed so a drain-cleaning tool can reach the entire run. For underground piping that is 2 inches in diameter or smaller, the maximum developed length between cleanouts is forty feet. Developed length means the distance along the pipe from one cleanout hub to the next, including fittings that add length. Keeping the run within 40 feet ensures a snake or auger can reach through the pipe to clear obstructions. Distances shorter than that would mean more cleanouts than necessary, while longer distances would risk having a blockage beyond reach.