According to code 2.4.7.1, where must every interior leader have a cleanout?

The requirement for a cleanout in every interior leader is crucial for maintaining drainage system functionality and facilitating maintenance. Positioning a cleanout at the bottom of the leader or no more than 3 meters upstream ensures that any blockages or build-up can be easily accessed and cleared without unnecessary dismantling of the system. This placement allows for efficient cleaning and inspection of the drainage system, which is vital for preventing potential clogs and ensuring smooth operation.

The need for a cleanout in this location is also supported by practical considerations, as it is typically the area where material buildup is most likely to occur due to the gravitational flow of waste. This approach adheres to plumbing codes intended to promote safety and maintain proper serviceability in plumbing systems.