What is the longest length of horizontal drainage pipe allowed before a cleanout is required?

What is the longest length of horizontal drainage pipe allowed before a cleanout is required?

• A. 50 ft
• B. 75 ft
• C. 100 ft
• D. 125 ft

Answer: (C)

Access for cleaning and maintenance in horizontal drainage runs is the key idea. Codes require a cleanout at intervals so you can snake the line without dismantling fixtures. The longest length allowed between cleanouts is 100 ft, meaning any horizontal run should not exceed 100 ft before you encounter a cleanout. This is why 100 ft is the correct choice. A shorter distance like 50 or 75 ft would still be compliant, but they aren’t the maximum allowed. A run of 125 ft would require a cleanout sooner to maintain accessible access for cleaning and inspection. Remember, some local codes or pipe sizes can modify exact spacing, but 100 ft is the standard maximum in common practice for exams.

Access for cleaning and maintenance in horizontal drainage runs is the key idea. Codes require a cleanout at intervals so you can snake the line without dismantling fixtures. The longest length allowed between cleanouts is 100 ft, meaning any horizontal run should not exceed 100 ft before you encounter a cleanout. This is why 100 ft is the correct choice. A shorter distance like 50 or 75 ft would still be compliant, but they aren’t the maximum allowed. A run of 125 ft would require a cleanout sooner to maintain accessible access for cleaning and inspection. Remember, some local codes or pipe sizes can modify exact spacing, but 100 ft is the standard maximum in common practice for exams.