What is Tonic Water?

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.

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.

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.

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.