Combine carrots, water, sugar and 1/2 teaspoon salt in slow cooker. Cover and cook until carrots are tender, 4 to 6 hours on low.
Drain carrots, then return to slow cooker. Stir in marmalade, butter and sage. Season with salt and pepper to taste and serve. (This dish can be held on warm setting for 1 to 2 hours before serving; loosen with additional hot water as needed before serving.)