In a medium saucepan, combine 1 ½ cups of sugar with 1 ½ cups of water. Heat over medium heat, stirring until fully dissolved, about 5 minutes. Remove from heat and cool.

Bring 4 cups of filtered water to a rolling boil. Pour water over 1 cup of dried hibiscus flowers and let it steep for 15 minutes.

Use a fine-mesh sieve to strain the hibiscus tea into a bowl, discarding the flowers. You should have about 4 cups of hibiscus concentrate.

In a gallon container, combine the strained hibiscus tea, cooled simple syrup, and the juice of 2 limes. Add 10 cups of cold filtered water, stirring well.

Cover the container and refrigerate for at least 1 hour. Serve over ice and garnish with lime wedges.