It may be a contentious subject amongst whiskey connoisseurs, but the science doesn’t lie; adding water to your whiskey can work wonders for releasing even more flavour and depth. But it’s not that simple, add too much and you dilute those flavours. So we’ve dived into the science to find out just why you should add water, and how much.

Adding water to whiskey  is a controversial topic these days. But it certainly shouldn’t be. The contention stems from the fact that some purists believe that adding liquid to the best of drams is a form of dilution that no serious whiskey drinker ought to take seriously. These self-styled whiskey connoisseurs are overlooking some fairly rigorous science that shows that the process of measured dilution can actually open up whiskey in some fairly compelling ways. 

Why add water to whiskey?

A recent study by chemists at the University of Sweden showed that adding water to whiskey boosts the concentration of flavour compounds at the surface of the drink, bringing more of those rich aromatics to the nose as we sip. Why add water to whiskey? And since a large percentage of perceived whiskey flavour is borne of smell—that’s a pretty easy way to increase taste sensations on the tongue. You can read more from the paper here. 

Lab data aside, the even more apt mantra to remember is one famously attributed to a prominent American bourbon maker. When asked the proper way to drink his beloved whiskey, without hesitation he answered: “Any damn way you please!” 

The perfect way to add water to whiskey

Temperature

So now that we’ve removed any persistent stigmas regarding water in whiskey let’s talk about how to do it. That is, the best ways to introduce water to whiskey in the service of flavour. There are a few things you want to take into consideration here and we’ll start with the temperature of the water that you’re bringing into the mix. As a general rule of thumb, when whiskey is served too cold, it can constrict some of those all-important flavour molecules and make the drink too short, reeling in what would otherwise be a lengthy finish. Conversely, if you serve a spirit too warm you can be over exciting some of the volatile compounds held within and increase the unpleasant “burn” that sippers associate with unhappy drinking experiences. A happy in-between is found between 11-14˚C (52-57°F) — roughly the cellar temperature of a good wine. If you’re using tap water, lift the lever straight up to the top; not to the left or right, to get the desired temperature.

Quantity 

Now let’s talk more about how much water to add to whiskey. In short: not too much. You can always add more water later, but you won’t be able to take out what you’ve already put in. So be very measured with how you introduce the water. Luckily for you, The Craft Irish Whiskey Co. has dedicated years of research to this very subject. We’ve always known that adding water could open up the flavours, but no one had ever drilled down on just how much water was needed. Until now. Our whiskey pipettes are precisely marked to show the perfect amount of water required for a 25ml and 50ml serving of water, so you’ll never need to guess again! Of course, if you don’t happen to have one of our whiskey pipettes to hand, you can always use a  small water decanter or carafe and make sure that you’re pouring into your whiskey dram ever-so-slightly. 

Technique

Once the drops have been added, swirl the combination of liquids around in the glass, covering the top with your hand. This will not only ensure that none of the precious nectar spills out, but will also help build up those flavour molecules within the empty space of the chamber. When you lift your hand off, you should smell all sorts of magic when you’re bringing it up to your nose.  

Glassware 

You can improve this whiskey-tasting experience further by using the right glass or stemware. When so much flavour appreciation starts with smell, you want to ensure you get the full flavour without the ethanol burn that can interfere with those complex notes. You’ll want something like an Erimon Glass or a brandy glass that curves inward, from a maximum circumference where the liquid sits, to channel those aromas through a smaller aperture at the top. 

Again, to save you the legwork, our award-winning designers have crafted a scientifically perfect rendition of such. It’s called the Érimón Glass, and it is one of the finest Irish whiskey glasses in existence. Using soda-lime glass instead of the more common crystal allows the ethanol vapours to be absorbed by the glass itself, which has a more amorphous molecular structure, and every element of the design works to facilitate this. A ‘vortex point’ at the base of the glass creates a tornado effect, swirling the whiskey molecules out to the side where the ethanol can be absorbed. The wider bulb shape aids this swirling motion and creates more surface area for the ethanol molecules to disappear into. The chicane slows the movement of the vapours as the aroma travels up the glass so more can be removed, and the divergent rim tips any remaining ethanol vapours over the edge and away from the nose. All the drinker is left with are the rich, layered notes of maple syrup, tobacco, chocolate, leather, fruit, spice or whatever flavour profile the whiskey master has created over the years with their barrels. 

Type of water 

Some people will make a fuss about the type of water you’re using and whether it’s de-ionized or purified. It’s important to note that regular tap water out of your kitchen sink will include all manner of mineral deposits and perhaps sanitising agents. And, yes, these can affect the overall flavour or your whiskey in negative ways. So consider using bottled spring water if you can. But if you can, make it the best water for your whiskey. This might take some experimentation to find the perfect water for the whiskey you drink, but what better excuse to drink more whiskey! 

Of course, if you don’t want to risk your whiskey with any old water, we’ve done the legwork so you don’t have to. In our pursuit of the perfect whiskey experience we’ve gone to the ends of the earth, quite literally. We spent three years searching the globe, tasting and testing before we found Hallstein Water. Not only is this the purest water in the world; bottled from a single aquifer 700ft below the earth’s surface in a UNESCO World Heritage Site in Austria’s Dachstein mountains, it also performs some kind of magical alchemy on our whiskeys, opening up the flavours and making the whiskey sing more than another water we tried. 

Enjoy it!

Other than that, have some fun—experiment with how much you add and see if you can find a sweet spot. This isn’t rocket science. It’s meant to be enjoyable. You’ll likely find that after you swirl, oak notes in the whiskey can become more distinct, and some of the more harsh notes in more aggressive whiskeys are diminished. Which is why this is a technique we recommend more for cask strength whiskey than we do for whiskeys bottled at the legal minimum of 40% ABV. 

You might even find that the mouthfeel of the whiskey evolves after adding water. Some prefer this evolution from fuller-bodied to something perhaps a touch creamier. It’s entirely up to you. And you won’t know your exacting preference until you’ve gone out and confirmed it. As the whiskey maker said, drink it any way you damn please. Now you know how to do just that.