Which hose diameter is commonly used for both supply and attack lines on engine work?

Which hose diameter is commonly used for both supply and attack lines on engine work?

• A. 1 inch
• B. 3 inches
• C. 2 1/2 inches
• D. 4 inches

Answer: (C)

In engine work, you want a hose size that delivers enough water without making the line hard to handle. A two-and-a-half inch hose hits that balance: it’s large enough to provide a solid flow for typical attack lines and still light and flexible enough to move, connect, and maneuver as you advance the line or feed water from a hydrant to the pump. Larger diameters offer more water but become heavy and cumbersome for quick, on-the-ground work, while smaller sizes can’t deliver the needed flow. That combination of workable weight, good flow, and compatibility with standard nozzles is why two-and-a-half inches is commonly used for both supply and attack lines on engine operations.