Measure juice into a 6-8 qt stockpot. Add water and stir. Measure sugar and set aside. Stir pectin into juice and stir. Bring to a full rolling boil, stirring constantly. Stir in sugar. Bring to another full rolling boil, one that cannot be stirred down. Stirring constantly, boil hard for 1 minute. Remove from heat. Skim off foam, and immediately ladle into hot glass jars, leaving 1/2-inch head space. Process for 5 minutes in a boiling bath water.