What is the difference between attack lines and supply lines?

• A. Attack lines deliver water to the fire scene; supply lines move water from the source to the pump or to another pumper
• B. Attack lines move water from the source to the pump; supply lines deliver water to the fire
• C. Attack lines are for ventilation; supply lines are for extinguishment
• D. Attack lines are larger diameter than supply lines

Answer: (B)

Attack lines and supply lines serve two different roles in getting water where it needs to go on the fireground. A supply line is the big hose that brings water from the source ( hydrant, drafting site, or another pumper ) to the pump so the engine can develop pressure. The attack line then carries that pressurized water from the pump to the nozzle to apply it at the fire. In other words, supply lines feed the pump, while attack lines deliver water from the pump to the fire. So the water path is source → supply line → pump → attack line → fire.