1. Revelation 8:11 (ESV)
  2. Exposition

How extensive was the devastation?

Revelation 8:11 (ESV)

11 The name of the star is Wormwood. A third of the waters became wormwood, and many people died from the water, because it had been made bitter.

A third of the waters from rivers and springs were contaminated, which resulted in many deaths. Obviously, those who survive also feel the consequences of this plague.