A Drop of the Good Stuff: Water’s Starring Role in Whiskey Production

May 10, 2022

by Gary Quinn

Whether you are in the pro or anti “addition of water to your whiskey” camp, it can be easy to forget the huge importance this life-giving liquid brings to whiskey.

The whiskey gatekeepers try to convince us that water and whiskey don’t mix – conveniently ignoring the fact that water is the biggest part of this three-ingredient elixir. Water is possibly whiskey’s greatest companion and no amount of whiskey snobbery can change the fact that it’s is a powerhouse in whiskey production. Around 60% of whiskey is water after all. 

The simplest test of water’s power is at the very end of production when you release a single drop of water into a glass of whiskey. The affect that this tiny amount can have on the aroma, flavour and sometimes the texture of the resulting liquid is quite remarkable and testament to the layers of alchemy that create it.

Most great distilleries have a unique source of water, such as Bushmills St Columb’s Rill, a tributary of the nearby River Bush; or the spring wells that feed the Dingle distillery in Kerry or the Liberties Distillery in Dublin’s inner city or the trout-filled Loch Measc that feeds the Lough Measc Distillery in Co Mayo. Some distilleries do use their region’s mains supply, although it’s rare they’ll advertise that fact in their marketing. Either way, whiskey is nothing without water. 

It takes a starring role in three main stopovers on the production journey: malting, mashing and cutting. Water doesn’t necessarily bring flavour to a whiskey but it does allow all the other actors to do their part and create that flavour – whether its in the yeast that’s used, the sugar water extracted from the wort, the repeated evaporation and return to liquid form during distilling, or the ebb and flow of the whiskey at the molecular level as it seeps into and out of the wood of the cask.

Here’s our guide to water’s starring role in whiskey making: 



Malting cannot happen without water. There’s a reason they call it Uisce Beatha – Water of Life – and that’s because the first main stage of creating whiskey is to create life, through germination. Until barley is dampened with water and then warmed to around 7 degrees, it cannot germinate. On its own. the heat will toast it and prolonged dryness will kill it but it’s not until water makes its entrance that life can begin again. Malting is essentially the process of tricking barley into germination. 

The addition of water and warmth makes the barley think it’s spring, and so, it starts to germinate and ready itself for another season of growth. This life-enhancing process sees the barley transfer the energy it has sapped up from the sun (starch) and converts it into sugar. This sugar is the fuel used during fermentation to produce alcohol. If we were to leave barley unfettered at this stage it would develop roots and dig towards the earth. 

But we don’t. It was all a trick to enable whiskey makers to harvest it further. We interrupt the germination process once the sugars have been created. We can see this process in action because, after about five days, the germinating barley will start to produce what are known as germs, but to our eyes are tiny shoots that would become roots. 



At this point we want to stop the growth because the sugars will be consumed by the growing germs, so to achieve that, we have to remove the water. We dry the barley again. If you want a peated whiskey this is the prime time to insert your smoke, by drying with a peat source or other smoky flavoured fuel. Once it’s dry, the barley is ground to a grist, which is a rough texture but not quite as fine as flour. 

Then it’s time for water to take its second spot in the limelight. The grist is mixed with hot water in a large tub called a mash tun. This was once always wooden but modern production has seen most mash tuns converted to stainless steel. Essentially, they are huge tubs within which the starch from the grist is heated and the sugars extracted in a liquid form known as wort. This sweet and rich sugar water is cooled and left to ferment. The grist that is left behind is usually given to farmers as animal feed. It’s still a rich and flavour-packed source of nutrition. 

The wort is left to ferment for between 48 and 96 hours and, during this time, yeast converts sugar into alcohol and a beer of around 9% is produced, ready for the next stage: distilling. 



Distillation is a long process of applying heat to the wort and reducing its volume while increasing its alcohol content as it passes through pot stills. No additional water is added during this process and the next time fresh water makes an appearance is after distillation. Before the casks are filled, water is added to the whiskey to reduce the alcohol level to around 64% ABV. This extra water helps the congeners in the spirit to release flavour more freely. At a higher alcohol level they’d be inhibited.

All whiskey will spend at least three years and usually a lot longer, in wooden barrels or casks. During this time water will evaporate and the whiskey will become richer. Once the distiller decides the maturation process is complete they will open the cask and have a cask strength whiskey. Fresh water is then used to cut the whiskey and reduce its alcohol level to the required amount. Cask strength might be 58% and the distiller will add water to reduce this to anything from 40% ABV upward. 

Dilution and enrichment are the ebb and flow of whiskey production and water makes this happen. We shouldn’t fear adding a drop of water to our whiskey glass, particularly if it’s a high-strength release. Doing so can get to the heart of the whiskey itself and reveal surprises you hadn’t expected.