A bottle of whiskey
How Much Water You Need To Add To Whiskey For The Best Tastings
In 2013, scientists at Washington State University conducted a study to figure out how much water should be added to whiskey for its full aroma and flavor profile to come through.
They diluted 25 different types of whiskies with increasing amounts of water and found out the perfect volume of water to add to your whiskey is 20%, and it's all based on science.
In the study, the sensory panel of experts could easily differentiate between each type of whiskey when they were undiluted and even when the amount of water was 20% of the drink.
However, when diluted with over 20% water, the whiskies started to smell similar. Since smell and taste are linked, this "likely affected the [...] flavor as well," the team noted.
The scientists examined the headspace — the area between the surface of the liquid and the top of the glass — and how the volatile compounds in the whiskies responded to water.
What water does to whiskey is a complicated business involving atomic density, but previous research shows that it partly comes down to a single molecule called guaiacol.
When a drink has a high alcohol by volume, such as whiskey, which is around 40%, the guaiacol reacts with the ethanol and the molecule moves further away from the surface.
That means it's all towards the bottom of the glass, not the top. Adding a little water helps the guaiacol float to the surface, delivering even more of that smoky taste and aroma.