What fraction of the world's fresh water supply is contaminated in the trumpet judgments?

ONE THIRD of the world's fresh water supply is contaminated in the trumpet judgments, as stated in

Rev. 8 : 10 - 11

10 The third angel blew his trumpet, and a great star, blazing like a torch, fell from heaven. It fell on a third of the rivers and springs of water.

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

The ceremonial column.