Charles Ellicott Commentary Exodus 17:3

"And the people thirsted there for water; and the people murmured against Moses, and said, Wherefore hast thou brought us up out of Egypt, to kill us and our children and our cattle with thirst?" — Exodus 17:3 (ASV)

To kill us. —This was no exaggeration. Thirst kills as surely as hunger, and more quickly. Whole armies have died of it. (Herod. iii. 26.) Ships’ crews have perished of it on the ocean, with “water, water everywhere, and not a drop to drink.” Unless a supply could somehow or other have been provided speedily, the whole people must have been exterminated.