Plus: Ultimate Thanksgiving Guide
Preheat the oven to 400°. In a large roasting pan, roast the turkey parts for about 1 1/2 hours, or until well browned; transfer to a large pot.
Set the roasting pan over 2 burners. Add 3 cups of the water and boil, scraping up the browned bits from the bottom of the pan. Add the liquid to the pot.
Add the onion, carrot, celery, garlic, salt, several pinches of pepper and the remaining 13 cups of water to the pot. Bring to a boil. Reduce the heat to moderately low, cover partially and simmer the stock for about 2 1/2 hours. Strain the stock and skim the fat before using.
The stock can be refrigerated for 3 days or frozen for up to 1 month.