17 May 2025
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Water in whisky (and why you should add it)

When it comes to whisky, water really is everywhere. Of all the ingredients used in whisky production across the world, none can be considered more important – not necessarily to the final product itself but for the fact that without it there would be no final product.

Whisky producers have long been aware of the importance of water. Visit any distillery and its source will never be far off. It may take the form of a babbling river, possibly once a source of power for the distillery too. It may not be babbling so much as lapping on the shores of a loch whose mirror surface is seen for miles from the surrounding hills. In fact, it may not be seen at all, absorbed within ancient peat bogs far below, drawn from a well. Or, it may flow through measureless limestone caverns far beneath bluegrass prairies, purifying as it goes.

Water, water, everywhere

The journey in whisky begins, of course, with rain. As rain falls it feeds rivers, soaks into peat bogs and replenishes aquifers. The process can take years; as Jim Murray notes in his Complete Book of Whisky, geologists at Highland Park in Orkney once estimated the water which runs from its spring today first fell on the Scottish mainland almost 200 years ago before embarking upon a 200-mile subterranean journey to the island.

And this is only the beginning. During germination, barley is steeped in water. Next, hot water is added to the mash bill in the mash tun. This is the water which will ultimately find its way into the bottled spirit. First, though, distillation must take place. At this point, water is often used to steam fire the copper stills, as well as during the cooling process. Once ready for barrelling, the distillate is diluted with water (often from the distillery source) to roughly cask strength. Finally, it’s matured, and if it’s not to be bottled at cask strength it is further diluted with water.

water drops

Is there something in the water?

Suffice it to say, water has much in the way of interaction with whisky during the production process. Whether its ultimate influence matches its physical importance, however, is a topic of much debate. In Scotland, soft water was traditionally considered superior to harder types. Several distilleries reliant on the latter have, however, long produced quality whisky. Likewise, the distilleries of Kentucky and Tennessee are reliant on particularly hard, calcium-rich water; it’s supposedly conducive to good yeast interaction during the fermentation process.

And what of the final product? It used to be thought that the water used by the distilleries of Islay, tinged brown from years of contact with peaty soils, was responsible for the characteristics of the islands’ whiskies – not the peat kilning. Even today, many distilleries will point to the sources of their water as being paramount in defining their individual products.

And yet at the same time, mashing is now often thought to leach so many of the minerals from water. And of course, there’s ferocity of the distillation process and the time distillate must spend in contact with wood maturing. Some will baulk at the thought of drawing water from chlorinated, community sources; no adverse effect caused, others claim.

The water is in your hands

It is perhaps well to suggest here that the most significant opportunity to influence whisky with water rests on the drinker. That could be in the form of ice, soda water or just a few drops to ‘awaken the serpent’. (On that note, imagine stepping outside after a rain shower. What do you smell? Tarmac? Earth? Grass? The fresh air? Water has a way of opening up scents and making flavours pop. Try some in your whisky – you might be pleasantly surprised).

Ultimately, though, there is no right or wrong answer – even if there is much debate. And the debate surrounding water and whisky on the whole will no doubt continue. But it is reassuring to know that as do the rains so will the whisky flow around the world – and there’s little point in debating that.

Close up of a person holding a dram of whisky in a Glencairn glass

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