Double and Triple Distillation

At Auchentoshan in Glasgow, every drop goes through three distillations, according to the producer.[5] It is a striking Scottish exception to a familiar pattern: most malt Scotch whisky is distilled twice, while Irish pot still whiskey is usually distilled three times. Neither pattern describes every whisky from its country.[1]

Double distillation takes fermented wash through two distillations; triple distillation adds a third. The distinction sounds simple. Following the liquid through the stills reveals a more interesting story.

What double distillation does

Double distillation begins with wash, the fermented liquid entering the first still. A review by researchers at Abertay University and the Scotch Whisky Research Institute puts its strength at 8% to 10% ABV, or alcohol by volume, in traditional copper pot still production.[2]

The Scotch Whisky Technical File describes a larger wash still followed by a slightly smaller spirit still. Vapour from the first distillation condenses into low wines, which collect in a receiver before passing through the second distillation.[1]

The second run is divided into foreshots or heads, the spirit cut or heart, and feints or tails. Only the heart is kept for maturation. Foreshots and feints return for redistillation with the next batch of low wines.[1][2]

That return journey is part of what “twice distilled” means in practice. The stills handle material carried forward from earlier runs, rather than a succession of entirely separate batches. For a closer look at this cycle, follow low wines and feints.[1]

Double and triple distillation compared

Follow the liquid, not the national stereotype. Double and triple distillation describe production routes. At Springbank and Mortlach, fractional counts describe arrangements in which portions with different distillation histories come together.[7][8]

A third distillation alone tells you neither the collection strength nor the cut points. It also leaves open how fractions are recycled. Those details explain what actually happens inside the system; simply counting the stills does not.[5][7][8]

What triple distillation means in practice

Auchentoshan gives a clear account of its process: the Glasgow producer says every drop is triple distilled, taking its fermented liquid from around 8% ABV to 81% ABV. Those published strengths describe Auchentoshan's spirit, rather than a specification shared by all triple distilled whisky.[5]

Bushmills says its single malt uses 100% malted barley and is triple distilled in copper pot stills.[6] The description identifies both the grain and the method. Irish whiskey as a whole has a wider range of permitted routes.[4]

Revenue's Irish whiskey verification checks accept double or triple distillation, with double as the minimum. They also distinguish the equipment from the distillation count. Pot Still Irish Whiskey must use a copper pot still, while Grain Irish Whiskey must use a column still; both may be double or triple distilled. Malt Irish Whiskey may also be double or triple distilled.[4]

That distinction matters. “Triple distilled” does not automatically mean three pot still stages. Irish grain whiskey makes the point neatly: the equipment used and the number of distillations are separate questions.[4]

Why some distillation counts are fractions

Springbank's “two and a half times” describes combined portions, not half a physical distillation. A 2014 profile in Brewer and Distiller International explains the route: some low wines are collected before the second distillation, then mixed back into the feints for another distillation. Some liquid therefore passes through twice and some three times.[7]

The same profile records one wash still and two spirit stills serving three approaches. Springbank uses partial triple distillation, Longrow is double distilled and Hazelburn triple distilled. The equipment is shared, but each product takes its own route through it.[7]

Mortlach's system is more involved, and its route is better established than its fractional count. A 2015 trade explanation by the Whisky Professor describes six stills, with one wash and spirit pair operating conventionally. Of the output from the other two wash stills, 80% goes to one spirit still. The weaker 20% goes to the small still called the Wee Witchie.[8]

Claim: Mortlach’s Wee Witchie distils the weaker portion three times.
Verdict: Documented

The trade account describes those three distillations and the subsequent combining of three streams.[8] Evidence gap: Who devised the system and when is not reliably established.

Earliest source in the supplied sheet: The Whisky Professor, 21 October 2015: https://scotchwhisky.com/magazine/ask-the-professor/7498/the-mortlach-conundrum
Last checked: November 2026.

Putting a single number on that combined spirit is less straightforward.

Claim: Mortlach’s fractional distillation figure is 2.7 or 2.81.
Verdict: Disputed

The same trade account reports both figures and calls 2.81 the official figure.[8] Evidence gap: The account does not independently establish which calculation should prevail.

Earliest source in the supplied sheet: The Whisky Professor, 21 October 2015: https://scotchwhisky.com/magazine/ask-the-professor/7498/the-mortlach-conundrum
Last checked: November 2026.

Springbank's and Mortlach's fractional counts describe systems, rather than the number of complete distillations experienced by every drop.[7][8]

Distillation strength is not filling strength

Spirit leaves the still at one strength and may enter the cask at another. The 2014 Springbank profile makes the distinction especially clear: its three malts have different spirit cut ranges, yet all three are reported as reduced to 63.5% ABV for cask filling.[7]

Springbank's cut runs from 76% to 60% ABV, Longrow's from 69% to 58% ABV and Hazelburn's from 79% to 63% ABV. Each range records the start and end strengths of the cut, not an average strength.[7]

For comparison, the Abertay and Scotch Whisky Research Institute review describes the heart of a conventional second distillation at around 70% ABV. It says the separation into heads, heart and tails depends on both alcohol strength and congener concentration.[2] Explore those fractions in the cut: heads, hearts and tails.

More broadly, the 2019 Scotch Whisky Technical File describes filling somewhere between 60% and 70% ABV, while the Scotch Whisky Association's FAQ gives 63.5% as usual.[1][3] When comparing figures, check whether they describe distillation or the moment the spirit enters wood.

The distillation count also says little about how close a spirit comes to neutral alcohol. The Scotch Whisky Technical File specifies distillation below 94.8% ABV without prescribing a number of distillations.[1] Auchentoshan's reported 81% ABV is a concrete example of triple distillation below that ceiling.[5]

What the number can tell you about flavour

Auchentoshan attributes strong fruit and citrus notes to triple distillation and says its spirit is more receptive to woody character from casks.[5] These are the producer's explanations of its own spirit, not findings from an independent comparison across distilleries.

The producer also calls it “the smoothest spirit”.[5] That broader claim does not demonstrate a sensory advantage over double distillation. Fruit, citrus and wood tell the reader more about the intended character than a general promise of drinking quality.

Springbank's processes show why the count alone makes a poor flavour label. The 2014 profile describes Longrow as highly peated and Hazelburn as non-peated, alongside their different distillation routes. A useful comparison needs both the peating description and the process, rather than just the words double and triple.[7]

The sources answer “how is it distilled?” more directly than “which tastes better?”. The research review explains conventional double distillation; the producer pages describe their own methods; and the Springbank and Mortlach accounts trace particular routing systems. Together they provide a detailed picture of production, rather than a controlled taste test.[2][5][6][7][8]

Common mistakes when reading distillation claims

Treating nationality as a process specification

Check the individual whisky before applying the national shorthand. The Technical File explicitly uses “usually” when describing the Scottish and Irish traditions.[1] Auchentoshan and Hazelburn are Scottish exceptions to the usual double-distilled malt Scotch pattern; Revenue's checks confirm that Irish whiskey can be double distilled too.[4][5][7] Neither national pattern covers every whisky from its country.[1]

Reading a fractional count literally

A precise-looking decimal still needs a source and an explanation. Mortlach's account reports both 2.7 and 2.81, calling the latter official without independently settling the calculation.[8] Read two and a half or 2.81 alongside the routing description, rather than assuming the figure records one identical journey for every drop.[7][8]

Using the count as a quality ranking

Separate a process claim from a judgement of drinking quality. Auchentoshan's praise describes its own triple distilled spirit, not an established advantage for all whiskies made that way.[5] Look instead for specific evidence about cuts, strength and intended character. More distillations is not, by itself, a reason to rank one whisky above another.

Where to go next

• How Whisky Is Distilled: follow the wider journey from wash to spirit.
• Reflux and Copper Contact: Lyne Arms, Boil Balls and Purifiers: explore another part of the distillation process.
• Distillation Strength and Congeners Explained: examine strength and the compounds associated with flavour.

Sources

1. UK Government. Technical File for Scotch Whisky, June 2019.
   https://assets.publishing.service.gov.uk/media/5fd36667e90e07662ed92c85/Scotch_Whisky_Technical_File_-_June_2019.pdf

2. Daute, M., Jack, F. and Walker, G. The potential for Scotch Malt Whisky flavour diversification by yeast. FEMS Yeast Research, volume 24, foae017, 2024. DOI: 10.1093/femsyr/foae017.
   https://pmc.ncbi.nlm.nih.gov/articles/PMC11095643/

3. Scotch Whisky Association. Scotch Whisky FAQs, undated web page, verified November 2026.
   https://www.scotch-whisky.org.uk/discover-scotch/faqs/

4. Revenue, Irish Tax and Customs. Irish Whiskey G.I.: Scheme of Verification Checks, document metadata dated 16 March 2023.
   https://www.revenue.ie/en/companies-and-charities/documents/excise/whiskey-verification-checks.pdf

5. Auchentoshan. Our process, undated producer account, verified November 2026.
   https://www.auchentoshan.com/our-process

6. Bushmills. About the distillery, undated producer account, verified November 2026.
   https://www.bushmills.eu/about-the-distillery/

7. Mitchell, B. Och! Campbeltown Loch... Brewer and Distiller International, May 2014, pp. 33 to 38. Institute of Brewing and Distilling.
   https://www.cibd.org.uk/media/5e2hin4o/5-campbeltown.pdf

8. ScotchWhisky.com, The Whisky Professor. The Mortlach Conundrum, 21 October 2015, trade explanation.
   https://scotchwhisky.com/magazine/ask-the-professor/7498/the-mortlach-conundrum

This desk research article uses verified fact sheet TOP-A439 and the supplied rulings, distinguishing research, official descriptions, producer claims and trade explanations.

Last checked: November 2026