Light water or Lightwater may refer to:
Science Deuterium-depleted water, which has a lower concentration of deuterium than occurs naturally on Earth Water, especially water that is not heavy water Water, the coolant in a light-water reactor, a type of nuclear reactor
Other uses Lightwater, a town in Surrey, England
See also Semiheavy water, a form of water in which one of the protium atoms in light water is replaced with deuterium atoms Heavy water, a form of water that contains a larger than usual amount of deuterium molecules Super-heavy water, a form of water in which both protium atoms in light water are replaced with tritium atoms