Deuterium or Hydgrogen-2 – What is it?

You may come across this question in a pub quiz one day, or when being chased down by the Chaser, maybe!

Water as a compound, and water molecules are generally accepted as being made up of two hydrogen atoms and one oxygen atom (H2O). But not all hydrogen atoms are created equal. Hydrogen has three naturally occurring isotopes, or variants. These are: Protium, Deuterium and Tritium.

‘Ordinary water’ is mostly made up of the Protium isotope, 99.99%. However, it also contains a very low percentage of the Deuterium isotope (D2O). Approximately one in 6400 hydrogen atoms is Deuterium, equivalent to 156 parts per million (ppm). Trace amounts of the Tritium isotope contribute even less.

Water with a higher concentration of Deuterium is often referred to as ‘heavy water’, because of its higher density, attributable to one extra neutron. Heavy water can effect biological reactions, and be toxic to humans, but at concentrations exceeding 50%, compared with the usual 0.0156%.

Deuterium was first discovered in 1931 by Noble laureate Harold Urey, andlater used in 1934 in one of the first biological tracer experiments to estimate the turnover of water in the human body. Heavy water is also used in nuclear reactors, bringing stability to the fission reaction, but is itself not radioactive.

Bottled water producers regularly must disclose physical, chemical, biological and radiological composition and contaminants of their source water and finished product. However, Deuterium is not usually tested for. Bottled water generally though has Deuterium content between 135 and 158 ppm (Source: National institute of Health).

Deuterium composition of the following waters is available and published.

  • Evian – 146 ppm
  • San Pellegrino – 148 ppm
  • Fiji Water – 149 ppm

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