Why is it important to know both static and residual pressures in firefighting?

Understanding both static and residual pressures is critical for ensuring an adequate water supply for fire suppression. Static pressure reflects the pressure in a water system when there is no flow, indicating the maximum available pressure at hydrants or within a fire protection system. Residual pressure, on the other hand, represents the pressure available when water is flowing and helps firefighters assess how much water can effectively be delivered during firefighting operations.

By knowing both pressures, firefighters can determine whether the water supply is sufficient for their needs. Adequate residual pressure is necessary to maintain flow rates needed to combat fires effectively. If residual pressure drops significantly when water is drawn from the system, it could indicate that the supply is insufficient, which may hinder firefighting efforts. This knowledge also helps in planning resource allocation and ensuring that the correct size of hoses and nozzles is utilized.

In contrast, options related to calculating total water usage, determining the cost of water services, or assessing water flow color do not directly relate to the critical operational need of ensuring an adequate supply for firefighting efforts. This makes the chosen answer the most relevant for the task at hand.