1. Place roast in 3 1/2 quart slow cooker. Add water until halfway up sides of roast. Cover.
2. Cook on Low for 7-9 hours or on High for 3 1/2-4 1/2 hours.
3. Remove roast.
4. Strain beef juice. Skim off any fat.
5. Add hot water to beef juice, if needed to make 3 cups.
6. Add bouillon powder, onion powder, salt and pepper. Stir.
7. Slice beef thinly. Insert slices into each bun.
8. Serve with a small bowl of beef juice for dipping.