Rinse the chicken well under cold running water and place it in a large stockpot. Add water to cover by 2 inches. Bring to a boil, then turn the heat down to a low simmer.

Simmer the stock for 3 hours, carefully skimming away any fat and impurities that rise to the surface with a ladle.

Remove the stock from the heat and strain it through a colander and then through a fine-mesh sieve, being careful to leave the sediment in the bottom of the pot. Degrease the stock again with a ladle.

Cool the stock in an ice bath. Store until ready to use: in the refrigerator for up to 1 week, or in the freezer for up to 2 months. Scrape off any congealed fat before using.