In a large jug muddle together 1/2 cup raspberries, 1/2 cup blueberries, 1/2 cup strawberries and the Queen Garnet Plum Nectar with the sugar until the fruit is mashed and combined. Stir through half of the kombucha, then strain the mixture through a fine mesh sieve and into a large pitcher or serving bowl or jug, pressing the fruit pulp to get all of the juice; then discard the pulp.
Add the rest of the kombucha, lemon juice, rosewater, and the rest of the fruit to the sangria. Cover and chill for at least an hour.
Fill glasses with ice, and ladle in sangria and fruit. Top each glass with a little sparkling water, and serve.