From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

("fount of the sun".) A spring on the border between Judah and Benjamin, N. of Judah, S. of Benjamin ( Joshua 15:7;  Joshua 18:17). Between "the going up to Adummim" (i.e. the road leading up from the Jordan valley) and the spring of Enrogel. E. of Jerusalem and of the mount of Olives. Now Ain Haud or Chot, "the well of the apostles," a mile below Bethany on the way from Jerusalem to Jericho. The sun's rays are on it all day.

Morrish Bible Dictionary [2]

Spring on the border of Judah and Benjamin mentioned next to En-rogel.  Joshua 15:7;  Joshua 18:17 . Identified with Ain Haud , 31 46' N, 35 16' E. The sun shines on this spring all day, answering to En-shemesh, 'spring of the sun.'