In a large bowl, mix marinara sauce with water; set aside.
Pour bread crumbs on a plate, and coat chicken pieces until well coated (there is no need for egg, it will stick to the wet chicken).
Take a manicotti shell and slide the chicken in it. Repeat until done. In a baking dish, put a thin layer of sauce, then place manicotti shells in dish.
Pour remaining sauce over everything. Cover tightly with foil and bake in a pre-heated 350 degree F oven for 1 hour and 15 minutes
Take out of the oven, and remove the foil and sprinkle the mozzarella evenly on top and put back into the oven until the cheese is melted; about 5 - 10 minutes.
