Club soda is a form of carbonated water manufactured in North America, commonly used as a drink mixer. Sodium bicarbonate, potassium sulfate, potassium bicarbonate, potassium citrate, or sodium citrate is artificially added to replicate constituents commonly found in natural mineral waters[1] and offset the acidity of introducing carbon dioxide gas (which creates low 3–4 pH carbonic acid when dissolved in water[2]).
Naturally effervescent Selters water from Germany gave rise to the generic use of the term for carbonated water, particularly from a soda siphon, in the United States as seltzer water. Seltzer water is artificially carbonated but lacks added minerals.[1][3]