'Spring' in the Bible

A spring does not pour forth from the same opening fresh and bitter [water, does it]?

A fig tree is not able, my brothers, to produce olives, or a grapevine figs. Neither can a saltwater spring produce fresh water.

And he said to me, "It is done! I [am] the Alpha and the Omega, the beginning and the end. To the one who is thirsty I will give [water] from the spring of the water of life freely.