1. Place turkey breast into a large slow cooker. Whisk onion soup mix and water in a bowl and pour the mixture over the turkey breast, spreading it out to evenly cover the meat.
2. Stir garlic powder, onion powder, parsley, seasoned salt, basil, and oregano in a bowl until thoroughly combined; sprinkle the seasonings over the turkey breast.
3. Cook on low until turkey is a very tender and the seasonings have flavored the meet. 8 to 9 hours. An instant read meat thermometer inserted into the thickest part of the breast, not touching bone, should read at least 165°F.