Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.
Spread the uncooked rice evenly across the bottom of the prepared baking dish.
In a bowl, mix together the cream of mushroom soup, cream of chicken soup, and water until smooth.
Pour half of the soup mixture over the rice and stir gently to combine.
Place the chicken breasts on top of the rice mixture.
Pour the remaining soup mixture evenly over the chicken.
Sprinkle the onion soup mix over the entire dish.
Cover tightly with aluminum foil and bake for 1 hour and 30 minutes.
Remove from oven, uncover, and let sit for 5 minutes before serving.