top-up with soda water

Soda water, also known as carbonated water, sparkling water, or club soda, is water infused with carbon dioxide gas under pressure, creating a fizzy beverage with a neutral pH when properly carbonated. The carbonation process involves dissolving CO₂ into purified or mineral water at cold temperatures, typically under 3.5–4 volumes of carbonation (a measure of CO₂ dissolved per volume of liquid). Soda water is distinct from mineral water (which contains naturally occurring minerals) and flavored sodas (which contain added sugars and flavorings); it contains only water and carbon dioxide, with minimal sodium in most commercial varieties unless explicitly added. The mouthfeel is characterized by a slight tartness and tingling sensation from carbonic acid formation when CO₂ reacts with water.

In mixology, soda water serves as a versatile lengthener and modifier, used to top up cocktails to dilute spirits, reduce alcohol content, and add refreshment without imparting flavor. It is essential in classics such as the spritz, Gin Rickey, and whiskey-sodas, where it constitutes 50% or more of the drink. Beyond cocktails, soda water is employed in culinary applications including the preparation of light batters for tempura and fried dishes (where its carbonation creates extra crispness), in dessert mousses and whipped preparations, and as a hydrating base for diluting syrups and cordials. It pairs particularly well with citrus spirits, gin, and whiskey, and is often combined with fruit juices and fresh herbs to create simple refreshing beverages.