In 5- to 6-quart slow cooker, mix carrots, potatoes and onion.
If necessary, cut corned beef brisket to fit into slow cooker; place over vegetables. Add enough of the water to cover. If brisket is packaged with spice packet, add contents of spice packet and omit pepper, cloves and bay leaf. If not, add pepper, cloves and bay leaf.
Cover; cook on Low setting 10 to 12 hours.
Remove and discard bay leaf. Remove brisket from slow cooker; place on serving platter. Cut brisket into thin slices. With slotted spoon, place vegetables in serving bowl.