How to Make It
In a large pot, combine the chicken, celery, carrots, onions, parsley, peppercorns, bay leaves, and 16 cups water. Bring to a boil, reduce heat, and simmer, partially covered, for 2 hours, occasionally skimming off and discarding any foam that rises to the top.
Strain the stock through a fine-mesh sieve and discard the solids. Let cool completely, then skim off and discard any fat that rises to the top. The stock can be refrigerated for up to 4 days or frozen for up to 3 months.