What is the maximum developed length between cleanouts for underground piping greater than 2 inches?

• A. 40'
• B. 100'
• C. 75'
• D. 50'

Answer: (C)

Access to the line for cleaning is the idea being tested. Cleanouts are placed so a plumber can reach and clear a blockage with typical cleaning equipment. For underground piping larger than 2 inches, the maximum distance you should have between cleanouts is 75 feet. That spacing strikes a balance between keeping the line reachable by equipment and not overdoing the number of cleanouts.

If the run were longer than 75 feet, a blockage could be beyond the reach of standard tools, making maintenance much harder. The other distances would either be tighter than necessary (increasing cost and complexity) or looser than allowed (risking inaccessible blockages).