Pour blackberries, peaches, brown sugar, cinnamon and water into slow cooker and stir until well combined.
In medium bowl blend together butter and flour and salt until well mixed and crumbly. Add in water slowly mixing until form a slightly sticky dough.
Sprinkle a clean surface lightly with flour. Pat out crust until ¼ inch thick. May shape to fit into slow cooker or simply slice into strips and place over berry mixture in slow cooker.
Cover and cook on lowest heat setting for approximately 1 hour and 45 minutes. Fruit will be cooked through with a thick syrup.
Pastry will be cooked but will be light colored and not browned like a traditional cobbler.
Recipe by Premeditated Leftovers™ at https://premeditatedleftovers.com/?p=9533