Preheat oven to 325°F
Spray casserole dish with cooking spray
Pour rice into casserole dish
Add two cups water
Place chicken on top of rice
Sprinkle garlic powder and black pepper over chicken
Cover casserole dish with foil
Bake 1 hour 30 minutes in preheated oven
Mix 1/2 cup water and mushroom soup
Uncover chicken
Pour mixture over chicken
Bake, uncovered, for 20 minutes
Serve