Spring
Starts under the ground and flows naturally to the surface. Must be collected at the spring or via a borehole that taps the underground rock formation that creates the source of the spring.

Distilled
A method where impurities are left behind as the water gets turned into steam, which is then condensed into pure water.

Mineral
Must come from an underground source and naturally contain at least 250 parts per million of minerals in the water—none may be added after the fact, according to the U.S. Food and Drug Administration.

Reverse osmosis
A method where water is pressurized through a membrane filter, leaving impurities behind.

Sparkling
Fizzy water that contains the same amount of carbon dioxide it had when it emerged from its source. Sometimes it can be treated in a way that removes the CO2, which is then equally put back in. Not to be confused with the soft drinks seltzer, soda water or tonic water.

Tap
Potable from most faucets in America, it can contain mineral additives like fluoride, which your dentist appreciates but you may not.