Which distribution system type is typically associated with an older layout and dead-end service lines?

• A. Tree (Trunk) System
• B. Grid-Loop System
• C. Ring System
• D. Branch Network System

Answer: (A)

In distribution layouts, the way the mains are arranged determines whether service lines end in dead ends. The trunk-and-branch setup uses a main trunk that runs through the service area with multiple branches extending outward to individual customers. This design was common in older systems because it’s simple and inexpensive to install. Because the flow typically runs out along branches that terminate at the customer, many service lines end in dead ends rather than looping back or connecting to multiple paths. That combination of a central trunk and outward, terminating branches is what makes this layout characteristically associated with dead-end service lines.

In contrast, grid-loop and ring configurations create interconnected paths that form loops, providing alternative routes for water to flow and thus minimizing dead ends. A branch network can have some redundancy, but the hallmark of the older, dead-end style is the trunk-and-branch arrangement.