Heat oven to 375 degrees. Spray 2 rectangular pans, with cooking spray.
Beat milk and eggs in large bowl with whisk. Stir in bread crumbs, onion, mustard, celery salt, nutmeg, salt, and pepper. Mix in beef until well combined. Shape into approximately 60 balls. Place in pans. Bake uncovered about 30 minutes.
Spray 5 to 6 quart crock pot with cooking spray. Place meatballs into the crock pot. Mix soup, water, and dill weed in large bowl; pour over meatballs. Stir to coat meatballs with the sauce.