What does water add to – or take from – your whisky?

What does water add to – or take from – your whisky?

After the release of a scientific study examining the effects of dilution on whisky, Whisky Magazine undertakes an investigation of its own to get to the matter's source
Alex Mennie

04 May 2023

For years the only controversy about water and whisky was over whether you should add a drop (or more) to your dram. Evangelists took up arms on either side of the great water debate and argued either that a splash of H2O “opens up” the spirit, or spoils the distiller’s art. Fortunately, those days are largely consigned to the past (dark corners of the internet notwithstanding), and you’ll find very few committed whisky drinkers, ambassadors or experts who will answer the question, "Should I add water?" with anything other than, "If you like."

If the question of whether to add water to whisky has been resolved, the next question must be how much should one add? Again, for some time now this has been left to personal preference, but a recent study, led by Washington State University, has now concluded that there is a point at which an individual’s preference may begin to adversely affect their enjoyment of the dram.

The study assessed the impact of differing ratios of whisky to water across a range of 25 samples, including bourbon, rye, Scotch and Irish whiskies, and concluded that while adding a little water had a noticeable effect on the smell of the whisky, at 80:20 whisky to water, the samples started to share the same aromas. By the time dilution reached 60:40, the trained sensory panellists were unable to distinguish them.

Tom Collins, a WSU assistant professor and senior author on the study, explains that these results are due to the way dilution affects what’s happening in the "headspace" in the glass. In short, more complex compounds, such as those associated with smoky aromas (particularly in peated whisky) or vanilla and oak (particularly in bourbons) disperse first, leaving fruitier aromas behind.

With science supporting the conventional view that some water will open up the spirit, but that ‘too much’ will drown it, the next variable to consider is the choice of water – a debate that opens up a whole world of complexity with argument and counter argument, science and faux science, and a lot of use of the word ‘pure’.

Free-flowing waters in Fife, Scotland


With a wide variety of waters available – tap, spring, natural mineral, and a number of offerings ‘designed for whisky’ – consumers can be forgiven for deploying a level of cynicism to a product that is consumed by everyone, but truly understood by very few. Natural mineral water, for example, a term found on a range of bottles from Buxton to Evian and beyond, is a strictly regulated legal designation (not unlike single malt Scotch whisky) and refers to a product from a recognised source that can provide stable mineral composition, is microbiologically pure, and is bottled at the source – which is expected to be the most prominent feature on the label – as a badge of provenance. As a result, it is fundamentally very different to the liquid that flows from your tap and can range in mineral content from close to zero to more than 1,500mg of total dissolvable solids per litre depending on its source.

Perhaps to avoid dazzling with too much science, or perhaps for their own commercial ends, for years those who focus on whisky have proposed that if you want to add water, you should use that which is as close as possible to the water that made the whisky. This is the basis of the preference for ‘branch water’ in the southern United States, where this is understood to mean water from the same river or stream the distillery uses for production.

It’s also the belief underpinning the Uisge Source brand, which supplies water from three highly regarded springs close to some of Scotland’s most popular distilleries. With differences in soil and rock types across the country, founder Graeme Lindsay explains that his brand is inspired by the variations this creates in the water from the main whisky regions. Water from the Highland region is generally hard (high in minerals), water from Speyside soft (low in minerals), and water from Islay has a higher natural acidity due to the impact of the local peat.

While Uisge Source recommends experimenting with different waters to accompany your dram, acknowledging that personal taste will play a big part in consumer preferences, Lindsay does believe that “waters with the same chemistry as the water used to make the whisky allow for greater appreciation of the dram”.
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Uisge Source


The Glenlivet 12 Years Old
  • Uisge Source Speyside brings out a dry, dusty wool-blanket note that I didn’t get from the same whisky undiluted, and maintains the classic pineapple flavours you expect from this dram.

  • Uisge Source Highland produces the wooden dustiness of an old wardrobe and a feinty sweaty note.



Ardbeg 10 Years Old
  • Uisge Source Islay makes this much more aggressive on the palate, but also adds a pleasant pink peppercorn and sage element.

  • Uisge Source Highland finds sweeter peat smoke and some soft salted caramel.



Buffalo Trace
  • Uisge Source Highland (Lindsay has not yet tackled Kentucky) leads to a nose that was resolutely bourbon and found a chunk of extra fruit and spice on the palate.


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For many, however, purchasing a tasting set of regional water may seem excessive, when a somewhat similar substance comes out of the tap in your home. Inspired by a belief that all water tastes basically the same, that their palates aren’t attuned to noticing the differences, and that when adding a couple of drops to a highly complex single malt the choice of water will have very little impact on the phenols, esters and aldehydes in your glass, some consumers opt for a simpler choice.

The Fife Arms in Braemar and the River Clunie


These are arguments that seem to make sense and are compelling enough to convince many of the finest whisky bars in the world to offer nothing but tap water to accompany their serves. Some simply for convenience, but others, like the Scotch Malt Whisky Society’s tasting rooms, on the back of experimentation and consultation.

John McCheyne, Scotch Malt Whisky Society (SMWS) master ambassador, explains that the society carried out taste testing amongst its team and members, comparing commercially available whisky waters to “the wonderful water that flows into our Scottish venues through the tap”. The members decided that the latter was “good enough” primarily because it was what they would enjoy their whisky with at home.

While Scottish tap water is often compared favourably to that from other parts of the UK, the SMWS does admit to the use of the public water supply in its London tasting room, which is presumably similar to that which flows into my home in the capital.
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London Tap Water


The Glenlivet 12 Years Old
  • Far more red fruit and light floral perfume.



Ardbeg 10 Years Old
  • On the nose, the same sage note that was drawn out by the Uisge Source Islay, but dominated by a honey syrup sweetness. On the palate, white wine notes and enhanced smokiness.



Buffalo Trace
More depth on the nose, but a rounder, flatter palate with less of the fruit and spice you would expect. Finishes with a punch of alcohol.
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Further north, however, where belief in the quality of the local water can take on an almost religious fervour, Bertie’s Bar at the Fife Arms has embraced the legend of nearby Ballater, which was ‘founded on its water’ after a local woman claimed bathing there cured her of scrofula in around 1760. As a result, the hotel bar decided it didn’t have to look too far from its doorstep to find the perfect accompaniment to its 365 whiskies, and it is Deeside mineral water that fills their jug.

Deeside Natural Mineral Water


Whisky ambassador Katy Fennema explains that with a low pH and a low mineral content (just 63mg per litre) the local water “doesn’t pack a punch, but will open up just about any dram you add it to” and was "a natural choice" for the intimate and luxurious surroundings of Bertie’s.
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Deeside Natural Mineral Water


The Glenlivet 12 Years Old
  • The nose was sweeter, with much more pineapple evident and some vanilla. On the palate the sherry spice came through much more strongly.



Ardbeg 10 Years Old
  • On the nose, it enhanced the coastal dampness, oiliness, and woodsmoke. The palate was much sweeter, very woody with less of the smoke, salinity, and spice on the tongue. Finishes with a soft kick of peat.



Buffalo Trace
  • Really amps up the raisin fruitiness on both nose and palate.


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With interest in the provenance of ingredients not limited to those listed on the menu, Bertie's Bar whisky ambassador Katy Fennema admits that choosing the most local water was a win-win for the bar, and satisfies those consumers that ask, "What’s in the jug?". But she is also a firm believer in the special role that romance and narrative can play in any whisky drinking experience, particularly for those who may have travelled a long way to drink whisky in a luxury Highland hotel and seek that additional connection to Scotland.

This romance is also accepted by certified water sommelier and CEO of Aqua Amore Michael Tanousis, but only insofar as it comes down to enhancing the relaxing or pleasant enjoyment of a dram. When it comes to the science, Tanousis is far more forthright and advises that it is crucial first of all that consumers understand the difference between natural mineral water (a highly regulated product), spring water, and table water, before seeking out a liquid that will either allow the core characteristics of the whisky to sing, or enhance a particular flavour note that you enjoy.

He gives examples from his own experiments, referring to a comparison of the effect that two different medium (around 600mg per litre of total dissolvable solids) mineral waters had on a sample of Laphroaig. While one “failed to retain the character that is key to a medicinal whisky” another “amplified the salty, briny, mineral quality” while with Lagavulin, a good pairing “enhanced the smoky bacon flavours and viscosity” while a bad pairing, this time London tap water, “introduced chemical and plastic flavours”.
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Evian


The Glenlivet 12 Years Old
  • The nose has bags more orchard fruit and plenty of depth. On the palate there’s a little spice and a little bite, overall this accentuates the sweeter caramel and vanilla notes to the detriment of the dram overall.



Ardbeg 10 Years Old
  • The water flattens the nose overall but brings out more vegetal / geranium leaf. The palate is more astringent, with more alcohol burn, a greater salinity and a hint of petrol.



Buffalo Trace
  • The nose is drier and less fruity overall, but retains a hint of red berry and the tannins of overoaked red wine. The palate is subdued and a little bitter.


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In my own tasting, I found my own choice of medium natural mineral water, Evian, to be one of the worst performers, but despite my experience, Tanousis believes that it is not as simple as avoiding minerals in the water you add to your whisky. While much of the marketing in this space doesn’t engage with the consumer in a meaningful way – focusing on fairly meaningless terms like ‘clean’ and ‘pure’ – it is possible, he says, to find a high-mineral water that may enhance the natural characteristics of the whisky. This could be a water that makes the dram more enjoyable, opens it up in a harmonised way, or takes it in a new direction.

Larkfire "wild water" for whisky


This is a decidedly different approach than the one that lies behind the Larkfire brand of ‘wild water’ which distinguishes itself by its neutral taste and describes the founders’ quest to find the ‘purest, softest water untainted by minerals or chemicals’ which can be used as a constant for comparison of different whiskies.
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Larkfire – Still


The Glenlivet 12 Years Old
  • A little woody and a little biscuity, but the vanilla notes, fruit, and spice seem diminished here.



Ardbeg 10 Years Old
  • Enhances the oily fish and creosote notes on the nose, and while some remain on the palate, the peat smoke is much diluted and the flavours feel a little subdued overall.



Buffalo Trace
  • The vanilla remains strong, but a little pepper has come to the fore on the nose, with Larkfire finding the rye in the mash bill to show off this bourbon’s spicy side. On the palate, there is more spice than with the mineral waters, but the overall impression is very dry.


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As with much in the world of whisky, true pleasure will lie in the palate of the beholder and experimentation will be key. While there is plenty to be said of the romanticism of a particular water with a particular whisky in a particular time and place, it can’t be the case that the aqua is just there to play a neutral supporting role to every dram. The best water for each individual whisky must be out there somewhere, just waiting to be tapped.

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