Aside from that one key difference between H2O and D2O – which gives heavy water about 10 percent greater density than regular water – these two water types are chemically the same, although deuterium does exhibit slightly different bonding behavior to regular hydrogen (which is also known as protium, by the way).

Due to such incidental consumption, now going back almost a century, there's been a longstanding question over whether heavy water tastes the same as regular drinking water – or whether its subtle isotopic variation yields a different taste that people may be able to perceive.

"However, Urey and Failla [the former being Harold Urey, the scientist who discovered deuterium] addressed this question in 1935 concluding authoritatively that upon tasting 'neither of us could detect the slightest difference between the taste of ordinary distilled water and the taste of pure heavy water'.".

In the last two decades or so, advancements in our understanding of human taste receptors have prompted a reopening of old cases like this – and in their new research, Ben Abu, Mason, and their team can finally confirm that there really is something a bit different about the taste of heavy water.

In tests with mice, however, the animals did not seem to prefer drinking heavy water over regular water, although they did show a preference for sugared water – suggesting that in mice, D2O does not elicit the same sweet taste that people can perceive.