In a large saucepan, combine the rhubarb and water. Bring to boiling; reduce heat. Cover and simmer for 5 minutes. Remove from heat; cool slightly. Strain rhubarb mixture, lightly pressing to remove all juices. Discard pulp. Add sugar and lemonade concentrate to rhubarb juice, stirring to dissolve sugar. Cover and chill for 2 to 24 hours.
To serve, combine rhubarb mixture with chilled lemon-lime beverage in a punch bowl or large pitcher. Serve over ice. If desired, garnish with fresh mint, lemon slices and/or rhubarb stick.