2 Kings 2:19-22

The people of the city said to Elisha, “Look, our lord, this town is well situated, as you can see, but the water is bad and the land is unproductive.” “Bring me a new bowl,” he said, “and put salt in it.” So they brought it to him. Then he went out to the spring and threw the salt into it, saying, “This is what the LORD says: ‘I have healed this water. Never again will it cause death or make the land unproductive.’ ” And the water has remained pure to this day, according to the word Elisha had spoken.