To a large pan on the stove over medium heat add the ground beef and onion break the ground beef and cook it though. Once cooked remove any access grease from the pan.
Once cooked stir in the taco seasoning, water, rotel, sour cream and refried beans stir well.
Spray a 9x13 baking dish with non-stick spray.
Add 1/2 cup of the crushed Doritos to the bottom of the baking dish, sprinkle half of the cheese over the Doritos, pour the taco mixture over the cheese and spread it out. Sprinkle with the remaining Doritos and cheese. Bake for 30 minutes.