In a large bowl, combine instant rice, cream of chicken soup, cream of mushroom soup, water, garlic powder, and pepper. Stir to combine.
Spray the inside of the Crockpot with non stick cooking spray or use a liner.
Place half the rice mixture in the bowl of a crock pot.
Place chicken breasts on top of rice mixture.
Top chicken breasts with remaining rice mixture.
Sprinkle onion soup mix on top of all ingredients.
Cook on LOW for 6 hours or HIGH for 4 hours.