Place chicken pieces in large pot. Cover with cold water (5 -6 cups). Add carrots, celery, and potatoes to water. Add salt to taste if you want. Cover and simmer on low heat about 2 hours until the chicken becomes tender. Add the rice, cover and cook over low heat for about 30 minutes until the rice is tender and most of the liquid is absorbed. Remove soup from heat. Pull the chicken meat off the bone ( if will practically fall off), discard bones. Return shredded pieces to pot. Stir well. Let cool. Store in the refrigerator or freeze.