In a large pot, combine water, celery, and onions over medium-low heat until onions are clear.
Add diced potatoes, chicken bouillon granules, water and salt, and pepper
Bring to a boil over medium heat and cook 15-17 minutes until potatoes are soft.
Melt butter in a saucepan.
As soon as the butter is melted, whisk in flour slowly.
Then gradually add milk to the flour mixture and whisk continuously.
Heat 5 minutes and pour into soup mixture.
Add salt and pepper.
Mix well until blended and let soup heat through.
Pour into bowls and top with shredded Cheddar Cheese, bacon bits and sour cream, if desired.