In a large saucepan, bring the water, potatoes, carrots, celery, onion, salt and pepper to a boil. Reduce heat; cover and simmer for 8-10 minutes or until vegetables are just tender. Remove from the heat; do not drain. Meanwhile, in a medium saucepan, melt the butter. Blend in flour. Add the milk all at once; cook and stir until thickened and bubbly. Add cheese and stir until melted. Stir into the undrained vegetables, return large saucepan to the heat. Add corn and ham; heat through, stirring occasionally.