What is the significance of the 10-20-30 rule in calculating available water?

The 10-20-30 rule is significant in calculating available water because it provides a straightforward method to evaluate how much water can be delivered based on the pressure present in the system. Specifically, this rule indicates that for every 10 pounds per square inch (psi) of pressure, a fire pump can typically deliver 20 gallons per minute (GPM) for the first 100 feet of hose. This means that understanding the pressure in relation to flow allows operators to estimate how much water can be effectively used in firefighting efforts, ensuring a reliable supply during operations. This consideration is crucial for fire departments to make informed decisions about pump capacity and water source reliability in various emergency situations.