Dasani™ is marketese for tap water.
By the way, Dasani™ does not come from a spring, it does not come from a well. It comes from municipal tap water. Yup. They're taking the same water you'd get from your kitchen sink, run it thru a "state of the art" reverse-osmosis filter, then add some mineral salts to give it flavor.
In fact, they're changing you a buck for salted Coke without carbonation or syrup. Aquafina is the same scam by PepsiCo.

Source: http://www.dasani.com/faq.html