In a medium saucepan, combine 1 ½ cups of sugar with 1 ½ cups of water. Heat over medium until the sugar dissolves, about 5 minutes.

Bring 4 cups of water to a rolling boil in a large heatproof container. Remove from heat and add 1 cup of dried hibiscus flowers. Cover and steep for 15 minutes.

Strain the hibiscus tea through a fine mesh sieve into a one-gallon container, pressing the flowers gently to extract flavor.

Pour the cooled simple syrup into the strained hibiscus tea and add the juice from 2 limes. Mix thoroughly.

Fill the gallon container with approximately 10 cups of cold filtered water. Stir well to combine.

Cover and refrigerate for at least 2 hours. Serve over ice and garnish with lime wedges or fresh mint leaves.