This is a popular Jamaican drink. Sorrel is also sold under the name dried hibiscus or Jamaica flowers.
Bring the water to a boil in a large pot. Add dried sorrel, ginger, lemon juice and zest, orange juice and zest, allspice berries, and cloves. Cover, and let steep overnight. Strain, and stir in brown sugar until dissolved. Chill in the refrigerator. Serve over ice.