Bring the water, butter, and salt to a boil in a medium saucepan over medium-high heat. Stir in the rice, reduce the heat to low, and cover the saucepan with a tight-fitting lid. Cook until the rice is tender and all the water has been absorbed, 15 to 20 minutes. Remove from the heat and let stand, covered, for 10 minutes.
Before serving, fluff the rice with a fork.
Yield: about 3 1/2 cups