Finely shred peels from 2 lemons and 2 oranges. Juice 2 lemons and 2 oranges.
In a 16 quart stockpot combine lemon juice, orage juice, and shredded peels.
Add 12 c water, 8 c apple cider , 1½ c brown sugar, 1 c kosher salt, 1 c fresh rosemary sprigs, 3 tbsp whole black peppercorns, 5 bay leaves, and 5 cloves garlic.
Cover; heat over high heat until mixture is steaming, stirring occasionally to dissolve sugar and salt.
Remove from heat. Add 12 c ice. Let stand until ice melts and mixture is cool.