A relay operation is most commonly used when:

A relay operation is particularly necessary when the water source is located far from the fire incident. This situation arises when there is an insufficient volume of water available through nearby hydrants or when the fire is situated at a long distance from traditional water sources. In such scenarios, fire departments often deploy multiple apparatus to create a supply line, enabling them to transport water over a distance to the fire. The relay operation facilitates a constant flow of water to the fire scene, ensuring adequate suppression efforts can be performed even when immediate access to water is limited.

Establishing a relay operation effectively maximizes the available resources and can improve overall fire-fighting efficiency in remote situations. By addressing the challenge of distance, fire fighters can maintain a steady water supply, which is critical for effective fire control and prevention of further damage.