Shuck corn and clean stray tassels off each ear of corn. Remove the stick of butter from the refrigerator and set on the counter to get to room temperature.
Place the corn in a 6.5-quart slow cooker. Pour the water in the slow cooker. Place the lid on top and cook for 3 hours on high. Do not remove the lid until cooking time is done.
Once the corn is cooked, drain the water. Place the stick of room temperature butter in the slow cooker, place the lid on and let the butter melt (about 5 minutes with heat off). Enjoy immediately or let sit covered until ready to eat.