Prepare the citrus juice: Squeeze lemon, lime, and orange into a small bowl or measuring cup.
Mix the base: Stir in honey or agave syrup until fully dissolved. Taste and adjust sweetness if desired.
Chill and mix: Fill a shaker or glass with ice. Pour in the citrus-sweetener mixture and shake or stir to chill.
Add sparkling water: Gently pour in sparkling water to maintain fizz. Stir lightly.
Serve and garnish: Pour into tall glasses with ice. Garnish with citrus slices, mint sprigs, or a twist of orange peel. Serve immediately.