"Seltzer water is water that has been infused with carbon dioxide under high pressure, which creates the bubbles," says
Toni Marinucci, MS, RDN, a registered dietitian with a master's degree in nutrition and dietetics. "In simpler terms, seltzer is carbonated water therefore the ingredients should just read carbonated water. If it is a flavored seltzer then the ingredients should read: carbonated water, natural flavor."
As long as it doesn't have large amounts of sodium or sugar, you can drink as much sparkling water as regular water - no limits.