No, a DEXA body scan will not show body water or water retention as a separate component.
DEXA measures bone mass (bone mineral content), fat mass and “lean mass”. Lean mass is everything that is not body fat or bone and therefore includes, muscle, organs, skin, connective tissue etc … and water.
Big changes in body water (caused, for example, by your menstrual cycle, steroid use, creatine, carb loading or depletion) will affect your lean mass result, but we cannot say what is ‘retained’ or ‘excess’ fluid/body water.
Typically, over the long term, body water is stable, so we can read changes in lean mass as a change in skeletal muscle mass. We advise that, where possible, you come to Bodyscan in the same physiological state for every scan.