In a large pot, combine 4 cups of water, salt, and sugar. (If you have a pot big enough to fit your turkey in, use it. If not, any 4-quart pot will work.) Place over medium-high heat and bring to a simmer, stirring occasionally, just until the salt and sugar are dissolved. Remove from the heat.

Peel the orange zest in strips using a vegetable peeler. (Reserve the zested orange for another use.) Add the zest to the pot along with the rosemary, thyme, garlic, bay leaves, and peppercorns. Stir in the remaining 12 cups of water. Let cool to room temperature.

Submerge the turkey in the brine, or put the turkey in a large brining bag or bucket and pour the brine over the top. Cover and refrigerate for up to 24 hours.

Before roasting, remove the turkey and discard the brine. Pat the turkey dry, and continue with cooking the turkey.