All gravity horizontal drains within or under a building shall be accessible through what?

• A. Manhole
• B. Sight-glass
• C. Cleanout
• D. Access door

Answer: (C)

Access to gravity horizontal drains inside or beneath a building is provided by a cleanout. A cleanout is a dedicated access point with a removable plug that lets you insert rods or plumbing tools, inspect the pipe, and clear blockages without tearing walls or floors. Placing cleanouts at key locations, like the base of stacks or where the line changes direction, keeps the system maintainable and prevents minor clogs from becoming major problems. Manholes are used for exterior sewer mains and aren’t practical or typically required inside buildings. A sight-glass only allows viewing flow and does not offer access for cleaning. An access door isn’t the standard plumbing access point for cleaning or inspection of interior drainage lines. So the correct access method for these drains is a cleanout.