Contradiction with Exodus 7:18
2 Kings 2:21 speaks of healing waters, whereas Exodus 7:18 describes water being turned into blood, resulting in undrinkable water.
Exodus 7:18: And the fish that [is] in the river shall die, and the river shall stink; and the Egyptians shall lothe to drink of the water of the river.
Contradiction with James 3:11
2 Kings 2:21 describes the purification of harmful water, while James 3:11 questions whether a fountain can send forth fresh and bitter water from the same place.
James 3:11: Doth a fountain send forth at the same place sweet [water] and bitter? [place: or, hole]
Contradiction with Revelation 8:11
In 2 Kings 2:21, the water is made safe, but Revelation 8:11 depicts waters becoming bitter and deadly through Wormwood.
Revelation 8:11: And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter.
Contradiction with Exodus 15:23-25
2 Kings 2:21 showcases healing of water, in contrast to Exodus 15:23-25 where water at Marah was initially bitter until Moses was instructed to make it sweet.
Exodus 15:23-25: And when they came to Marah, they could not drink of the waters of Marah, for they [were] bitter: therefore the name of it was called Marah. [Marah: that is Bitterness]