The Egyptians digged round about the river for water Josephus says, they lost their labour, and found only blood there: but if they found water, or water less bloody, it is not material to us, as it does not lessen Moses's miracle, it not being within the compass of his commission to prevent their getting water by digging.
Related Commentaries of Exodus 7:24
Exodus 7:24
24 And all the Egyptians digged round about the river for water to drink; for they could not drink of the water of the river.