Pour 2 cups of the water into a 2-quart or larger saucepan (large enough for the brine and submerged pheasant) with the 3 Tablespoons of salt. Bring to boil and stir to dissolve salt.
Remove from heat, pour in remaining 1 cup water and stir well. Cool completely before using (I cool about 30 minutes at room temperature then refrigerate for 1 hour). DO NOT put pheasant in before completely cool. Getting the brine cold first helps to prevent bacterial growth.
Submerge pheasant in brine, cover and refrigerate for at least 1 hour or up to 4 hours, but no more or it will be too salty!
Roast Pheasant
When you are ready to roast the pheasant, take the bird out of the refrigerator, rinse off the brine with cool water, and pat dry with a paper towel. Place it on a cast iron skillet and let it sit at room temperature for about 15 minutes while you preheat the oven to 475 degrees F.
Brush the pheasant with duck fat. If you don't have duck fat, you can use olive oil or melted butter. Sprinkle the pheasant all over with kosher salt and black pepper.
Roast the pheasant uncovered for 15 minutes at 475 degrees F. Lower the temperature to 350 degrees F, and cook about another 15 minutes until it reaches an internal temperature of 155 degrees F using an instant read meat thermometer.
Transfer pheasant to a cutting board and let rest, uncovered, for 15 minutes.
Carve pheasant, season with more salt and pepper to taste, then serve.