Homemade Rootbeer

5 gallons cold water
5 pounds white sugar
1 (2-ounce) bottle root beer concentrate (you can buy it in the spice section of most stores)
5 pounds dry ice (you can get this at Smith's or Winco)

Place 4 gallons of the cold water in a large container. Add sugar and stir until dissolved. Pour in root beer extract and mix. Add the dry ice and put the lid on loosely so the gas can escape. Be sure that no one touches the dry ice with bare hands. It can freeze-burn skin in less than 5 seconds. Let it brew for about 15 minutes. Add the last gallon of water and let brew for another 15 minutes. Serves about 30 thirsty people who come back for seconds and thirds. You can also cut the recipe in half to serve about 15.