When can the water supply for attack lines and backup lines be drawn from the same source?

Using the same source for both attack lines and backup lines is appropriate when there is an engineered water system in place. An engineered water system is designed with features that enhance reliability and manage water flow effectively, ensuring that sufficient pressure and volume are available simultaneously for multiple lines. This system avoids the issues of water supply depletion that can occur when two lines draw from a non-engineered or shared source, which could lead to inadequate water for firefighting efforts.

In contrast, drawing from the same source during emergencies may introduce risks, especially if the source does not have guaranteed capacity to support multiple lines. Similarly, relying on full water tanks may not ensure consistent supply during active firefighting because tanks can drain quickly under high-demand situations. During training exercises, it is typically advisable to keep the setups simple and separate to prevent complications related to water supply management.