There’s no evidence to back that up. The Institute of Medicine recommends that men get about 125 ounces of water daily and that women get 91 ounces, but that includes water from all foods and beverages. Most people get enough hydration unless they’re exposed to heat stress or they’re very active for a long time.
This move hits all the muscles used in a pull-up, as well as all your core muscles. Grasp the handles with straight arms and tubing taut. Pull the handles towards you and lean back a little. Focus on bringing your shoulder blades back and together. Pause and slowly straighten arms back to the starting position without bending forward.