Exodus 7: 19-25
And the Lord spake unot Moses, Say unto Aaron, Take thy rod, andstretch out thine hand upon the waters of Egypt, upon their streams, upon their rivers, and upon their ponds, and upon all their pools of water, that they may become blood: and that there may be blood throughout all the land of Egypt, bot in vessels of wood, and in vessels of stone.
And Moses and Aaron did so, as the Lord commanded; and he lifted up the rod, and smote the waters that were in the river, in the sight of Pharaoh, and in the sight of his servants; and all the waters that were in the river were turned to blood.
and the fish tat was in the river died; and the river stank, and the Egyptians could not drink of the water of the river; and there was blood throughout all the land of Egypt.
And the magicians of Egypt did so with their enchantments: and Pharaoh's heart was hardened, neither did he hearken unto them; as the Lord had said.
And Pharaoh turned and went into his house, neither did he set his heart to this also.
And all the Egyptians digged round about the river for water to drink; for they could not drink of the water of the river.
And seven days were fulfilled, after that the Lord had smitten the river
Moses and Aaron are obedient to God and using the rod turn the waters into blood. Pharaoh's heart remains hard set against God and the children of Israel. He calls for his magicians who duplicate what Moses and Aaron had already performed - turning the water into blood. Why wouldn't Pharaoh request of his magicians to turn the blood back into water? Did Pharaoh and the magicians truly recognize that God's power is greater than their magic? Did they know that they had no power other than what God would allow? His people the Egyptians need to dig to find water to drink. Pharaoh's pride would not allow him to yield to God.
There will be times that God will send us out with specific instructions. And though we are obedient to those specific instructions the enemy will come with a deceptive duplication. It is frustrating when some impostor rises up to steer people away from the Lord. Being obedient and submissive to God means doing no more nor less than instructed. Moses and Aaron didn't get involved in a competition with the magicians. They trusted God. When in obedience to God, Moses and Aaron turned the water into blood, it was in order that Pharaoh would let the children of Israel go to worship the Lord their God. For what purpose did the magicians turn the water into blood? Scripture does not say that Moses and Aaron engaged with the magicians nor does it say that they were flustered by them. I believe that it was God's mercy that allowed the Egyptians to find water to drink. God is merciful to a people even when their leaders are ungodly.