What defines a manual standpipe system?

A manual standpipe system is designed primarily to allow firefighters to connect hoses and deliver water for firefighting purposes. This system relies on an external source of pressure to ensure water flow to the hoses operated by firefighters.

The correct answer highlights that a manual standpipe system requires pressure from a fire department pumper truck through a Fire Department Connection (FDC). This method is essential because the system by itself does not have the capability to deliver adequate water pressure needed for effective firefighting — it needs the fire department to boost the pressure when they connect their equipment.

In contrast, a system that operates independently of external water sources would not fall under the category of a manual standpipe, as it would imply a self-sufficient system, which is not the case here. Similarly, options discussing automatic detection and suppression or functioning without firefighters misrepresent the characteristics of a manual standpipe, as these would involve automatic or independent systems contrary to the function and purpose of manual standpipes.