As per NFPA 1142, there must be reliable _____ sources for the duration of any live-fire evolution.

In line with NFPA 1142, it is essential to have reliable water sources available during any live-fire evolution. The primary purpose of these water sources is to ensure that firefighting personnel have the capability to effectively control and extinguish a fire during training exercises. Water is the most common and effective medium for fire suppression, and having a dependable supply is critical for safety and the success of the exercise.

Other sources like gas or propane may be relevant in certain contexts of fire scenarios, but they do not serve the same purpose as water in live-fire drills. Hoses are important for delivering water, but without a reliable water supply, hoses alone would be ineffective. Therefore, the focus on water sources aligns with best practices for safety and effectiveness in live-fire training environments.