What is relay pumping and why is it used?

• A. A method of transferring water from a distant source to the scene by connecting successive pumps to maintain supply
• B. A method of measuring water depth
• C. A method of filtering water
• D. A method of increasing engine speed

Answer: (A)

Relay pumping is a method of moving water from a distant source to the fire scene by linking several pumpers in series. The first engine drafts water from the source and pushes it into a supply line that feeds the next engine’s suction; that engine then discharges into the next, and so on, until the final pump delivers water to the attack line with enough pressure and volume. This arrangement overcomes long distances, friction losses, and elevation changes that a single pump can’t handle, allowing a steady, adequate supply where water isn’t immediately available at the scene. It’s used when the source is far away or otherwise not readily accessible, so multiple pumps are needed to maintain the needed flow.