Albert Barnes Commentary 2 Kings 2:21

"And he went forth unto the spring of the waters, and cast salt therein, and said, Thus saith Jehovah, I have healed these waters; there shall not be from thence any more death or miscarrying." — 2 Kings 2:21 (ASV)

The spring of the waters - The spring intended is probably the one now called Ain es-Sultan, which is not much more than a mile from the site of the ancient town. It is described as a large and beautiful fountain of sweet and pleasant water. The springs issuing from the eastern base of the highlands of Judah and Benjamin are, to this day, generally brackish.