Is it true that adding water to whisky improves its flavor?
The burning, pungent qualities contributed by the high proportion of alcohol in whisky can make it hard to evaluate nuances. Adding water dilutes the alcohol, which reduces the burn and allows other properties to reveal themselves. But there’s also something significant happening on a molecular level. Aroma molecules share more chemical likenesses with alcohol than they do with water. As such, they tend to bind with alcohol. Adding water frees up more of the aroma molecules to evaporate into the taster’s nose. Since appreciation of flavors happens at least as much in the nose as on the tongue, “watered-down” spirits actually seem more flavorful.
To experience the science at work, we had tasters sip 1 1/2-ounce samples of 80 proof whisky neat and then with water added in increasing 1-teaspoon increments. While they noted that the neat sample of whisky had aromas of honey and caramel, flavor comments fell mostly in line with descriptions like “boozy” and “lots of burn.” With just 1 teaspoon of water added, the alcohol receded and tasters picked up on sweet, vegetal flavors and subtle aromas like hay and apple. Most tasters preferred the addition of 2 teaspoons (which diluted the alcohol to 65 proof), allowing flavors such as vanilla, apple, and pear to really come to the fore. By 3 teaspoons the whisky began to taste watered down to many tasters, though one found it beneficial to add up to 5 teaspoons.
THE BOTTOM LINE: Adding a little water to whisky will open up the nose and bring out more nuanced flavors, but the ideal amount of water will vary depending on the drinker.