Place Chicken, Onion, Bell Pepper And Celery In A Slow Cooker. In A Medium Bowl Combine The Tomato Soup, Cream Of Mushroom Soup, Tomato Paste, Water, Parsley, Oregano, Basil, Salt And Pepper. Mix Well And Pour Mixture Over Chicken And Vegetables In Slow Cooker. Stir To Coat And Add Bay Leaf. Cook On Low Setting For 8 Hours, Until Chicken And Vegetables Are Tender.