Not all of it. Once the water is purified, the manufacturer doesn't have to tell you where it comes from. The balance of bottled waters does come from protected springs or wells and is naturally free of disease-causing microorganisms and chemical contaminants. The FDA requires bottlers who use these terms to document that their water actually comes from the source they're claiming. There's no such thing.
Most water contains tiny amounts of harmless substances, including algae, fungi and bacteria.
In fact, bottled water may be more vulnerable to bacteria once it's open than tap water. Bottled water usually doesn't contain any chlorine, which is added to municipal water systems to stop the growth of bacteria. The longer an opened container of nonchlorinated water sits out, the more likely it will develop bacterial growth. This is unlikely to be a health risk, as these bacteria generally are not disease-causing. If you're buying gallon-size or larger containers of water, though, you're better off keeping them in your refrigerator.