What would happen to red blood cells in the body if blood lost through injury were replaced with pure water?

Water that is added would tend to equalize the amount of sodium and other substance inside the cell with what is outside the cell. Since the RBCs have more inside them, the pure water would move into the cell. This would cause the RBCs to swell and perhaps burst. The amount of water that is added to the blood would determined if the cells would burst. More pure water, the more likely the cell will burst.