From the producer:
TASTE: Our Club Soda has a silky smooth texture created by using the finest spring water (which has a low mineral content) and a high level of carbonation; it has no aroma so it can more effectively bring to life the flavors of the premium spirit it’s being mixed with.
KEY INGREDIENTS: Our Club Soda is our simplest product. After our natural spring water is carbonated with lots of very fine bubbles, we add Bicarbonate of Soda, which is used to add a minerality that enhances naturally occurring flavors in the spirits it’s paired with.