Mix 1 cup of warm tap water and 1 tsp yeast in small bowl. Check the water temperature and be sure it does not exceed 85 degrees Fahrenheit. Cover and let stand five minutes to activate the yeast.
Pour 8 cups of granulated sugar in the cooler and dissolve it with 2 quarts hot water. Add 3 1/2 gallons cool water.
Add yeast mixture and an appropriate amount of flavoring in accordance with package instructions. Stir to mix evenly.
Distribute soda into plastic bottles and screw caps on tightly. Store for five days at room temperature, approximately 70 degrees Fahrenheit. Refrigerate overnight before serving. Some yeast sediment settling at the bottom of the bottles is normal.