Open and drain canned clams, add the drained juices into stock pot and add the water, turn on stove to medium heat to warm.
Cook bacon in a cast iron skillet, remove bacon onto paper towels and drain the bacon grease into a bowl.
Add the Onions to heated cast iron skillet and add just enough bacon grease or butter to saute onions just until soft, not brown. Then add 1-2 tablespoons more of the bacon grease or butter and sprinkle the flour to make the roux/paste.
Add a cup of the clam juice and water mixture to the onion roux and then add the this mixture to the stock pot with the remaining clam/ water juice.
On medium heat continue heating until pot comes to a boil. Turn off heat and slowly add the heated milk and cream.
Now add clams, potatoes and chopped bacon, and simmer until heated through, salt and pepper to taste.