וַיַּחְפְּר֧וּ כָל־מִצְרַ֛יִם סְבִיבֹ֥ת הַיְאֹ֖ר מַ֣יִם לִשְׁתּ֑וֹת כִּ֣י לֹ֤א יָֽכְלוּ֙ לִשְׁתֹּ֔ת מִמֵּימֵ֖י הַיְאֹֽר׃
And all the Egyptians digged round about the river for water to drink; for they could not drink of the water of the river.
Read halakhic rulings (Jewish law) on Exodus 7:24: and classical halakhic sources.