You can make these kombucha coolers spiked or sober. To go the boozy route, you'll want to combine 3/4 cup of the watermelon kombucha mixture with 1 ounce (2 tablespoons) tequila. If you're mixing to order, simply use this ratio. Kombucha has a subtle effervescence, but if you want even more bubbles, I’d recommend adding a splash of fizzy soda water.
You can add extra ice to the glasses if you want the mixture colder, or shake up individual portions in a cocktail shaker and strain into glasses if you’re a purist. I always find it easier to throw everything in a pitcher, ice included and serve that way.