Water has no flavor but it changes the flavor of whiskey so much and it doesn’t make sense
In: Chemistry
You can think of it like adding water to juice concentrate. it just loosens everything up, making the flavours less intense and therefore more detectable.
When whiskey ages, the alcohol evaporates and the alcohol content drops slightly, causing it to smooth or mellow out. Adding a small amount of water is a way to artificially lower the alcohol content of whiskey, making it taste like an approximation (albeit less flavorful) of how that whiskey would taste if it were aged for a long time.
the chemicals that give the ‘burn’ of whiskey can bind to water. if you add a drop of water, they stick to the water and sink lower than the now purer ethanol. Therefore your first few sips are only the ‘good’ chemicals. unfortunately the last part of your drink now sucks.
Spirits expert here. To get to the bottom of this, we need to understand the properties of alcohol (in this case, ethanol) and water molecules. Alcohol is a much bigger molecule than water and tends to electrostatically “trap” other molecules, collectively called “congeners,” that give whiskies their distinctive flavors. Basically anything that’s not water or alcohol is a congener. Due to the molecular shapes of ethanol and water, they have a property with each other known as “miscability,” where their molecules are so arranged that they mix almost perfectly. If you had an ounce of pure ethanol and mixed it with an ounce of pure water, you’d end up with just a little more than one ounce of the mixture.
When you add a drop of water to whiskey, that property basically causes the water molecules to squeeze in between those ethanol molecules, freeing the volatile congeners and allowing them to evaporate into the air. This will enhance and change the aroma of the spirit, as your nose’s olfactory receptors are responsible for most of how you perceive whiskey. (Try holding your nose and taking a sip of whiskey some time…it won’t be very good.)
This effect is most pronounced with high proof or barrel proof whiskies, as they have the highest proportion of ethanol to water. Since most whiskey is bottled at 40% alcohol, the remaining 60% is mostly water. Adding a bit more usually won’t do too much to open it up.
Ultimately what it comes down to is that flavor compounds in the whiskey will be perceived differently in your mouth & nose depending on the alcohol concentration of the drink. Certain flavor compounds, for instance, tend to be present more towards the surface of the liquid when the ethanol concentration is lower ([source](https://www.livescience.com/60158-why-whiskey-tastes-good-diluted.html)). At higher concentrations, those molecules tend to instead be “locked up” away from that air-liquid boundary, where they can’t evaporate and get into your nose. So a lower alcohol concentration can give you a richer sense of taste because the same molecules are more readily perceived.
However, most whiskey is sold already at or near these lower concentrations where flavor compounds can shine. So adding water is not going to do much for all whiskeys. And it’s not the *action* of adding water in the moment that does anything – it’s just the concentration that it achieves. If you want your whiskey at 40%, and it’s already sold at that concentration, then that’s no different (except maybe in price) from buying a bottle at 45% and watering it down.
Ultimately it’s not much more magical than the difference between e.g. drinking lemonade vs. drinking a lemonade syrup. The syrup is very concentrated and will taste overpoweringly of sugar. Diluting it with water brings out more subtle flavors to the drink. The chemistry is a bit different, but the principle is the same: stronger concentrations don’t always make for the most pleasant or identifiable flavor experience.
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