David compares the water to blood because the men risked their lives to bring the water to him. He uses a question to emphasize this. This rhetorical question can be translated as a statement. Alternate translation: "Drinking this water would be like drinking the blood of those men who have risked their lives to bring it to me." (See: [[rc://en/ta/man/jit/figs-rquestion]] and [[rc://en/ta/man/jit/figs-metaphor]])