Instructions
- Make the syrup. Simmer the sugar, water, and rosemary in a small pot, stirring until the sugar dissolves. Take it off the heat, steep 20 minutes, strain, and chill. It keeps up to 2 weeks in the fridge.
- Mix the base. In a pitcher or drink dispenser, stir together the grapefruit juice, lime juice, and cooled syrup. Taste and add more syrup if your grapefruit is very tart. Refrigerate until the party.
- Add the bubbles last. Right before guests arrive, top with sparkling water and stir gently once. Stirring too much flattens it.
- Serve. Pour over ice and garnish each glass with a grapefruit wheel and a rosemary sprig.
Hosting tip: For a big crowd, set out the base in a drink dispenser with a bucket of iced sparkling water next to it. Guests fill their glass halfway with base and top it themselves, so every drink stays fizzy all night.
Make it ahead
The syrup can be made up to 2 weeks early. The juice base holds for 24 hours in the fridge. Juice the grapefruit the day before so party day is just pouring.
Variations
Swap the sparkling water for a non-alcoholic sparkling wine for a fancier toast. Use thyme instead of rosemary for a softer herbal note, or blood oranges in winter for a deeper color.
What you'll need
- 2-gallon glass drink dispenserHolds a full batch for 24 guests
- Citrus juicerMakes fresh juice for a crowd painless
- 12 oz highball glassesThe right size for this pour
- Non-alcoholic sparkling wineFor the fancier toast version
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Questions
Can I use bottled grapefruit juice?
Yes. Choose a not-from-concentrate juice from the refrigerated section. It's often less tart, so start with less syrup and taste.
How far ahead can I make it?
Make the syrup up to 2 weeks ahead and the juice base up to 24 hours ahead. Add sparkling water only right before serving.
How do I make it less sweet?
Cut the syrup in half and add an extra squeeze of lime. Grapefruit varies a lot, so always taste the base before adding bubbles.
Is this safe for pregnant guests and kids?
It contains no alcohol. Grapefruit juice can interact with some medications, so if a guest takes prescriptions, it's worth having a second drink option.



