Sparkling water is plain, unflavored carbonated water; seltzer water is also plain, unflavored carbonated water that is sometimes, but rarely, enhanced with minerals; club soda is carbonated water with subtle flavoring in the form of mineral ingredients and sodium. Ingredients commonly added to club soda for flavor include potassium sulfate and potassium bicarbonate.
Seltzer water and club soda are two widely available carbonated beverages, both either commonly consumed plain or used as ingredients in mixed beverages. While the terms "seltzer" and "club soda" are sometimes used interchangeably, subtle flavor differences make these two types of sparkling water useful for different purposes. Some cocktails that incorporate seltzer water include the Brandy Rickey and the New Orleans fizz. Seltzer can also be used for non-alcoholic beverages such as the egg cream. Some popular cocktails made with club soda are the mojito, the Singapore sling and the Tom Collins.
The name seltzer comes from the German village of Selters and its famed natural springs. Seltzer's first introduction to the American marketplace was as a less expensive substitute for carbonated mineral water. Seltzer water was once commonly packaged in heavy glass bottles with metal siphon caps. These types of spray bottles were popular in 20th-century slapstick comedy. In the contemporary beverage marketplace, both seltzer and club soda are packaged very similarly, albeit with different labeling, usually in plastic bottles.