Fill a slow cooker halfway with water. In a metal bowl that fits snugly in the slow cooker but doesn't touch the bottom, combine the water, oats, milk, nutmeg and salt. Place bowl in the cooker, cover and cook on low for 7-8 hours.
Stir the cherries into the oats and let sit for 10 minutes before serving. Serve oatmeal with maple syrup and butter.