You can make homemade iced tea. Boil 8 cups water in a pot. take off heat, add 3 'black tea' bags, cover 10 min, take bags out, flavor with up to 3/4 cup sugar or use sweetener, 1/3 cup lemon juice, and flavors like cranberry juice, or whatever you want. you can make this decaf, or use herbal tea. CHILL!!
The problem is, if he's a soda junkie, he may not want to quit. Send him to rehab!