Cook 4 slices of bacon in a skillet and then take the bacon out of the drippings. After allowing the bacon to cool, pinch bacon into small pieces and put back into the drippings. Using the same skillet over medium-high heat, stir the flour into the bacon drippings and cook, stirring constantly, until lightly browned (do not overcook). Slowly pour the water or milk into the flour mixture, add the salt and pepper and continue whisking until reaching the desired thickness. Add diced tomatoes, stir and simmer for an additional 5 minutes. Serve over hot halved biscuits.