Which of the following is not a condition that must be met before you begin to install a DWV system?

The correct choice reflects a requirement that does not need to be fulfilled prior to initiating the installation of a Drainage, Waste, and Vent (DWV) system. While it is critical to have a functioning plan and necessary permits in place for work to proceed legally and safely, notifying the building inspector specifically is not inherently a precondition for commencing the installation process itself.

In the context of plumbing work, securing permits and having a clear disposal plan for waste are essential steps that ensure compliance with local codes and regulations. The existence of a valid water supply line is also a key component to consider because the plumbing and drainage systems need to be compatible in terms of function and safety. However, notifying the building inspector is typically part of the compliance process that occurs after the essential preparations for installation have been made, rather than a prerequisite for starting the plumbing work.

The awareness of timelines, inspections, and permits is important for plumbing professionals, but the act of simply notifying the inspector does not directly impact the initial stages of DWV system installation. This makes it clear why the notification of the building inspector is not classified as an initial condition.