Heavy water, scientifically known as deuterium oxide (D₂O), is a water variant where the typical hydrogen atoms are replaced with deuterium, a heavier isotope. This substitution results in physical properties distinct from those of regular water, including a higher density and a slightly elevated boiling point.

Historically, heavy water has been integral in nuclear reactors as a neutron moderator.

When most people hear the term water, or even heavy water, the first thing that pops into their mind is taking a drink of it. You’ll be happy to know that even respected scientists have the same intrusive thoughts.

In the 1930’s, Klaus Hansen, who was a pharmacologist at Oslo University, decided to drink it to see what would happen. He described the experience in Time:

“I lifted the beaker to my lips. Immediately I felt a burning dry sensation in my mouth and then I could feel nothing. First my mind became excited and impressed with a feeling of crisis. I had some shock. Then I said to myself, ‘Be quiet—you are simply going through a minor experience.’ Then it was all over. I could see, hear, breathe, feel and walk just as before.”

He continued the experiment by increasing the amount that he drank over time, explaining:

“Within the next few weeks, I shall either be seriously ill or able to tell what the effects are, for I intend to raise the dose by easy stages during the next fortnight to the final and testing drink of 100 grams.”

Regarding safety, heavy water is generally considered non-toxic in small quantities.

The Yale School of Medicine notes:

“Studies over more than 30 years have not shown any negative consequences of deuterium administration.”

So, while it is definitely not recommended to drink heavy water (if you can even get your hands on it), there shouldn’t be any significant issues if you do drink a little bit, especially if it is in your water supply naturally.

If you thought that was interesting, you might like to read a story that reveals Earth’s priciest precious metal isn’t gold or platinum and costs over $10,000 an ounce!