Bring water and barley to a boil in a saucepan over high heat. Cover, reduce heat to low, and simmer until barley is tender, about 30 minutes. Remove from heat, drain if necessary, and chill barley in the refrigerator.

Combine cooled barley, corn, beans, onion, bell peppers, carrot, celery, chipotle pepper, oil, salt, black pepper, and cumin in a large salad bowl.

Make vinaigrette: Whisk together water, cilantro, corn syrup, oil, lime juice, lemon juice, vinegar, and onion powder in a medium bowl. Pour vinaigrette over barley mixture and toss to combine. Refrigerate salad until thoroughly chilled.