In a large Dutch oven or stockpot, saute the onion in butter for 3-4 minutes.
Sprinkle in the hashbrowns and saute for another 3-4 minutes.
Pour in the chicken broth and water; stir well to combine ingredients. Bring to a boil, then cover and reduce heat to a simmer and cook for 30 minutes...stirring occasionally.
Stir in the soups and milk and continue to cook for 15-20 minutes, to heat thoroughly.
Add salt and pepper to taste, then serve immediately with garnishes, as desired.
This is a thin soup, so make a slurry of 1 T. cornstarch with 1 T. cold water and stir well and add to soup to thicken, if desired.