Light water or Lightwater may refer to:

• 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

• Lightwater, a town in Surrey, England

• 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

This disambiguation page lists articles associated with the title Light water.
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