ingredients

• 2 oz. ginger (by weight, no need to peel)
  
• 7½ c. cold water
• 6 oz. sugar (by weight)
  
• ⅛ t. active dry yeast
• 2 T. lemon juice

instructions

1. Place ginger and ½ cup of the water in a mini-chopper (a blender might work), and puree.
2. Combine ginger/water and sugar in a small saucepan.  Stir over medium-high heat until sugar has dissolved. Remove from the heat, cover and let rest for 1 hour.
3. Strain syrup into a measuring cup.  It should be relatively cool by now.
   
4. Funnel the syrup into a clean 2-liter bottle, followed by 4 cups of the remaining cold water (this should be enough to bring the combined temperature of the syrup and the water to or below room temperature).  Now add the yeast (you probably want to do this without the funnel, so that the yeast doesn't get stuck), followed by the remaining 3 cups of cold water.  Cap tightly, shake, and leave at room temperature for 48 hours.
5. Store in the refrigerator for up to 2 weeks.  Make sure to open at least once or twice a day to release excess carbonation.