Bring a large pot of lightly salted water to a boil. Cook elbow macaroni for 8 to 10 minutes or until al dente; drain, and set aside.
Brown ground beef with garlic in a large skillet over medium heat. Strain off fat, if necessary. When meat is lightly browned, add carrots and cook until tender, about 5 minutes. Stir in zucchini and oregano, and continue cooking another 5 minutes. Season to taste with salt and pepper.
When vegetables are tender, stir in tomato soup, water, and prepared elbow macaroni, and cook for another 5 to 10 minutes. Serve with crumbled feta cheese on top, if desired.