What is Tonic Water?
Carbonated water flavored with quinine, sugar, and citrus. The mixer of the Gin and Tonic; not a substitute for soda water in a spritz or Americano.
The basics
Tonic water is a flavored carbonated mixer whose defining bitter is quinine, originally from Cinchona bark, now usually added as a purified compound. Sugar and citrus oils complete the formula. A Gin and Tonic is gin, tonic, ice, and typically lime; the tonic is the modifier, not a neutral lengthener.
Using tonic in a Campari spritz or a whiskey highball produces a drink that tastes like a G&T with extra ingredients, because quinine and sugar are not silent.
How it tastes
Quinine bitterness, citrus oils, and a substantial sugar load in most commercial tonics. Inexpensive tonic can taste of candy and quinine extract; drier premium tonics (Fever-Tree and similar) let gin botanicals remain audible. Flat tonic is sweetened quinine water without texture.
Where it comes from
British colonial practice combined gin with quinine tonic as an antimalarial measure; the sugar in commercial tonic made the medicine palatable. The combination survived as a highball long after the medical rationale receded. Twentieth-century supermarket tonic made the drink ubiquitous and, in many bottlings, sweeter than the gin.
The structure remains a highball: spirit plus a flavored carbonated mixer.
How to use it
Plenty of ice, cold tonic, and a lime wedge or peel. Ratio is taste; start around 1:2 gin to tonic so the spirit is not lost. Do not use flat tonic.
Do not pour tonic into recipes that specify soda water.
What pairs with it
Cocktails with Tonic Water
Recipes in the MixWise library whose specs call for this ingredient.
Gin
Gin and Tonic
A snappy, effervescent mix of gin and quinine-laced tonic that turns bitterness into refreshment.
Vermouth
Vermouth Tonic
A low-ABV highball of vermouth lengthened with tonic and citrus.