Bring the water to a boil in a medium saucepan over high heat. Add the butter and salt, then stir in the rice. Return the water to a boil. Reduce the heat to low, cover and cook until all the liquid is absorbed, 17-20 minutes (probably longer if making a larger quantity.) When all the liquid is absorbed, turn off the heat and let the rice stand covered for about 5 minutes. Fluff with a fork and serve.