Pour 1/2 cup water in Crock-Pot. Wrap precooked 3 to 4 pound ham in foil, place in Crock-Pot.
Cover and cook on High 1 hour, then Low 6 to 7 hours or until ham is hot.
If desired, sprinkle ham with liquid smoke before wrapping in foil.
If cooking larger ham, cook 1 houron high then low 8 to 10 hours.