The Science Behind Adding Water to Whiskey

Posted by Irish Whiskey USA on

Does whiskey really taste better with a splash of water?

Liquor Loot Blog: Joel Hauer, Founder & whisky sommelier 18 Aug 2022 

You’ve probably heard the adage that a small splash of water can help a whisky’s full flavour come out. If you participate in whisky tasting, you may have even experienced this phenomenon for yourself. But is there any actual science behind this idea of watering down our whisky just a pinch to get the full tasting experience? It turns out the answer is yes, and the science involved is pretty interesting.


In reality, water doesn’t add flavour to whisky so much as it prompts the whisky’s natural flavours to be more noticeable. You’ve probably never heard of guaiacol before, and that’s understandable. It’s a pretty strange word. Guaiacol is an aromatic oil that ends up in whisky via wood creosote, which is a byproduct of the charred wooden barrels whiskies are typically left to age in. Guaiacol is also the most prominent cause of that recognizable smoky flavour unique to whisky.

 For the record, there tends to be a smidge more guaiacol in scotch than in the many other types of whiskies because scotch is made from partially germinated barley or smoked over a peat fire, both of which are ways to add a little extra guaiacol to the mix.

Water brings guaiacol to the surface

If guaiacol is responsible for a lot of a whisky’s flavour, then more guaiacol should, in theory, automatically translate to more flavour, but this isn’t always the case. Guaiacol doesn’t mix smoothly into whisky, especially the higher proofs. It has a bad habit of clumping together and its density often leaves it meandering near the bottom of your whisky glass. There are two ways to win at this game of flavour hide-and-seek. You can either find a way to drink from the bottom of the glass, or you can coax the guaiacol into migrating back towards the top of the glass and, consequently, your mouth.


Assuming you don’t want to plunk a plastic straw into your delicious dram, you’re going to want to opt for the latter strategy. Alcohol and water don’t mix very well, and a small splash of water is actually enough to disrupt the guaiacol reserves and send some of them floating to the top of the glass.

How much water is too much?

So the science confirms that water can unlock your whisky’s full flavour, but how much water should you add? You don’t want to overdo it and risk watering down your expensive drink. Most people swear by just a few drops of water every couple of sips, while others insist a greater dilution is the way to go. Bourbon, for example, is such a robust drink that many experts say it can be diluted to a 1:1 ratio of water and whisky without sacrificing any flavor.

 Everyone’s tastes are different, so there is no “standard” amount of water to add to your whisky. Add a few drops before each sip until you think it tastes just right. Be sure to measure the water beforehand so you know exactly how much you’ve added. Be sure you’ve measured out your starting amount of whisky, too.

 Of course there’s nothing wrong with just winging it, either. Whisky drinking is only as serious as you want to make it. So don’t worry if you’re just casually tossing a spoonful of water into your drink now and then without keeping track. If it tastes good, then you’re doing it right.

Your perfect whisky proof

When you add water to your whisky, you’re diluting the proof. If you care to discover just what you’re diluting your drink to, then there’s a handy equation to help you out.


([original quantity of whisky]/[water added + original quantity of whisky]) x (bottle proof) = your new whisky proof.


Using this equation can be an easy way to determine the standard amount of water to add to your whiskies for that perfect flavour.

Can you substitute ice for water?

Whisky cocktails almost always call for ice and many people order whisky with a few ice cubes floating about. In theory, leaving a few ice cubes in your whisky will achieve the same guaiacol-moving result. However, there are risks to this approach. Temperature greatly affects how we perceive taste, especially with drinks. So taking your whisky on the rocks will open up the flavour a bit, but it may taste different to you than a whisky diluted with a few drops of room temperature water. In the end it is a matter of personal taste, so go do a little experimenting of your own!

 And the next time your bartender suggests a small splash of water be added to your neat whisky, you’ll know that they’re not just trying to save money by skimping on your bourbon.

This article originally appeared here.

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