Place turkey breast into slow cooker. Whisk onion soup mix and water in bowl and pour the mixture over the turkey breast, spreading it out to evenly cover the meat.
Stir garlic powder, onion powder, parsley, seasoned salt, basil, and oregano in bowl until thoroughly combined; sprinkle the seasonings over the turkey breast.
Cook on LOW until turkey is tender and the seasonings have flavored the meat, 6-8 hours. Meat should not be pink and easy to pull apart. (Meat thermometer inserted in thickest part of breast should read at least 165 F)