In a large skillet, cook beef over medium heat until no longer pink; drain.
Remove beef and keep warm. In the same skillet, combine the water, tomato sauce, chili powder, garlic powder, salt if desired and cumin; bring to a boil. Stir in spaghetti; return to a boil.
Boil for 6 minutes.
Add the zucchini. Cook 4-5 minutes longer or until spaghetti and zucchini are tender, stirring several times. Stir in beef; sprinkle with cheese.