Standpipe systems are built to bring water from an exterior or building water supply up through a high-rise, delivering it to fire hose outlets on each floor. Vertical risers run the water upward, and hoses can be connected at various levels so firefighters on arrival have immediate access without immediately pumping from outside at every floor. These systems can be filled with water at all times (wet standpipe) or kept empty and charged when needed (dry standpipe), but either way the goal is to have a ready water supply accessible at each floor outlet. A cistern stores water but isn’t by itself a complete distribution system to every floor’s outlets. Cross feed describes sharing water between different feeds or standpipes, not the primary mechanism that delivers water to hose connections on all levels. The term “dry bed” isn’t a standard way to name a high-rise fire-water distribution system. That’s why the standpipe option best matches the scenario.