Judgment comes in the form of the rivers and springs of water becoming blood (again, see Exodus 7:14–25 for a parallel, though not to be equated). Blood is life (Leviticus 17:11), provided it be in the body; blood outside the body is death. With the rivers and springs all becoming blood, there is only Death in the land, in step with Genesis 2:17. As with the second bowl, the emphasis needs to lie here on the prevalence of Death. In Revelation 16:6 we will receive some more detail as to significance of this plague.
4 The third angel poured out his bowl into the rivers and the springs of water, and they became blood.