Place a dutch oven over medium-high heat. Cook bacon until browned and crispy. Remove to a paper towel-lined plate to drain.
Add the shrimp to the dutch oven and cook it in the bacon fat, until pink all the way through, about 2 to 3 minutes per side. Remove to a cutting board.
Drain all but 2 tablespoons of bacon fat from the pot. (If there is not enough fat in the pot, add a little unsalted butter to make 2 tablespoons of fat total.)
Stir together the flour and Old Bay seasoning. Add flour mixture to the pot and whisk together. Cook for 1 minute.
Pour evaporated milk into the pot, whisking constantly to avoid lumps. Whisk in milk, water, and carrots. Reduce heat to medium, and cook for 7 to 10 minutes, or until the soup begins to thicken.
Chop up about 3/4 the shrimp. Add the chopped shrimp and almost all of the bacon to the soup, stir to combine. Cook for 1 to 2 more minutes.
Portion soup into 4 bowls. Distribute the whole shrimp between the bowls, placing it in the middle of the soup. Top the soup with the remaining bacon and a sprinkle of parsley. Serve warm.
Notes
If you prefer a stronger seafood flavor, you can substitute seafood stock in place of the water.