Problem: Exodus 7:20 asserts that “all the waters that were in the river were turned to blood” by Moses. But only two verses later it says the magicians of Egypt performed the same feat (v. 22), which would have been impossible if Moses had really turned all the water to blood.
Solution: First, it should be noted that “all” need not be taken in an absolute sense, but in the popular sense of “the vast majority.” Further, it does not say that Moses turned all water to blood, but only all the water “in the river” (Ex. 7:20). There was still water from wells that were unaffected. Then too, some of the water may have been filtered out through the sand on the river bank. This may explain why it says the Egyptians “dug all around the river for water to drink” (v. 24), since it would act as a natural filter for the river water.
