The beverage industry and various government agencies generally agree on the following definitions. They help explain the difference between water that comes out of your tap and what can be bottled and sold at a premium price in stores.
Natural water comes from a protected spring or well, as opposed to water from a municipal system or public source.
Spring water is derived from an underground formation from which water flows naturally to the earth's surface.
Well water is from a hole bored, drilled, or otherwise constructed in the ground which taps an aquifer.
Natural sparkling water is water from a protected spring or well that naturally contains carbon dioxide, making it bubbly.
Mineral water is from a government-approved and regulated underground source or natural spring; mineral content is not changed by the manufacturer.
Sparkling water is another name for carbonated water.
Seltzer is generally tap water that has been filtered and carbonated.
Club soda is generally tap water that has been filtered and carbonated with minerals and mineral salts added.