The Gemara and shulchan aruch pasken that one can drink water before havdalah. Is sparkling water that is carbonated (seltzer)considered water in halacha or a different beverage?
It is permitted to drink water before havdalah. Is carbonated water (soda) considered “water” or not? We make no blessing over water, unless it is drunk to quench thirst, because water has no taste. Carbonated water, however, is a beverage drunk because of its distinct taste, and therefore one would have to make a berachah over it. It would seem that the permissibility of drinking water before havdalah is because drinking water is not considered “drinking” — whereas drinking beverages (that have taste) is considered “drinking.” Therefore, it would not be permitted to drink carbonated water before havdalah.
A further line of reasoning is that Chazal only permitted “water;” carbonated water is not called “water,” but has a distinct name (soda, sparkling water, etc.), and therefore cannot be included in the permit to drink water. This also seems to be the standard position taken by poskim.
Sources: Tur and Shulchan Aruch, Orach Chaim 299:1 (permission to drink water); Maharsham, III:375 (soda water is not considered water); Pischei Halachah, chap. 4, note 29 (does one make a berachah on carbonated water when one is not thirsty); Vezos Haberachah, p. 311 (Birur Halachah 41) (carbonated water is considered drinking, whereas ordinary water is not); Shevet Ha-Kehasi, II:123 (based on the reasoning above, prohibits drinking carbonated water before havdalah); however, see Nishmas Shabbos, p. 635, who writes that carbonated water has the same halachic status as regular water.