We’re accustomed to vodka producers touting the base ingredients used to make the spirit (single-vintage potatoes! upcycled whey!). They even boast the elaborate distillation and/or filtration methods used in pursuit of pristine quality. And increasingly, vodka-makers are emphasizing the water source used to make, dilute and “finish” their product. But, do these water sources make a difference, or is it marketing, pure and simple?

Among the recent vodkas reviewed for Wine Enthusiast, label highlights included “deep ocean mineral water” (Ocean Vodka); “glacier-fed spring water from Mt. Hood” (Timberline Vodka); “Appalachian mountain water” (P1 Vodka); and “artesian spring water from West Louisiana” (Louisiana Tradition). But, what do these really mean? We took a deep dive into the waters to find out.

How Is Water Used in Making Vodka?

For starters, it’s important to know that water is used at least twice in vodka production. (For more, check out our guide to how spirits are made).

The first step in making vodka is fermentation, explains Tony Abou-Ghanim, author of Vodka Distilled. In this step, water is combined with raw ingredients—whether grain, grape, potato etc., creating a mash. The addition of heat and yeast, which feed on the sugars in the raw materials, induces fermentation.

The fermented mash is then distilled, which concentrates the alcohol. In brief, the mash is poured into a still and heated to a boiling point, so vapors rise. Those vapors are then cooled and condensed into liquid form. After the distiller removes the “heads” and “tails” (removing unwanted impurities), the remaining portion (the “heart”) may be re-distilled (sometimes multiple times, in pursuit of so-called purity and/or neutrality).

At this point, the alcohol level may be as high as 96% alcohol by volume (abv) (192 proof), so a considerable amount of water is added to dilute the concentrated distillate to a palatable level, usually around 40% abv (80 proof).

An important distinction is that the water used in fermentation isn’t always the same as that used to dilute the spirit after distillation. Many producers deliberately select water from a particular source for dilution; some refer to that usage as “finishing” the vodka.

“Most producers insist on using the best quality of water in their vodka,” says Abou-Ghanim. Some use distilled water, or local tap water that has been filtered and purified, he explains. Still, others obtain water from proprietary sources claimed to be free of any pollution to begin with–such as wells, protected reservoirs, springs, lakes, glaciers or pristine mountain run-off.

“Regardless of [the] source, water added to the spirit must be free of minerals, impurities and other contaminants,” Abou-Ghanim notes. “Otherwise all [the] time, money and effort spent producing a quality distillate are wasted.”

How Important Is Water Quality in Vodka?

In general, an estimated 60% of the volume inside a bottle of vodka is water. Based on that percentage alone, water quality is obviously important.

“If that’s terrible water, it will be a terrible product,” warns Caitlin Bartlemay, head distiller at Oregon’s Clear Creek Distillery and Hood River Distillers. For example, she warns against using “stale” water that’s been sitting in a tank for days. “Even water in a glass on your night table can taste stale by morning,” she says.

While water quality matters to all spirits, Bartlemay says, it’s particularly important in making vodka.

“You have no place to hide,” she explains. “Vodka has such subtle flavor and aroma. If you’re using inferior water, it’s like trying to paint a masterpiece on the back of a burlap sack… All the effort you put into your raw ingredients, all the work and labor you’ve done to create a superior and beautiful product, you throw it all away with a dollar store frame. Your water is extra important not to obscure your work.”

The Flavor Difference

The bottled water industry, which started to take off in the U.S. in the 1970s and 1980s, may have helped jump-start the trend of transparent water sourcing: from Evian to Fiji, many consumers have at least some awareness about where their H2O originates.

“These last couple of generations of consumers have been trained through water marketing to pay more attention to water,” Bartlemay notes. “It’s not a new thing to be calling out the integrity of your water source.” More recently, concerns about the impact of climate change have drawn more people to care about the origin and stewardship of their water.

When it comes to vodka, while it may look clear in the bottle, trace amounts of salts and minerals can affect the flavor, aroma and texture of the spirit.

“For the longest time, vodka was defined by the [Alcohol and Tobacco Tax and Trade Bureau] as being made from neutral spirits, meaning alcohol devoid of odor, color and taste – which was never really true,” says Bill Scott, Master Distiller for Hawaii’s Ocean Organic Vodka, which is made with desalinated deep sea water.

“There is some character that can be built in,” he explains, describing water as “a big carrier of flavor for the product.”

Elsewhere, Timberline vodka uses Hood River glacier meltwater. Bartlemay describes the water as “not overly mineral-rich” and containing no sulfur or iron. That neutrality in the water contributes to a crisp texture, she adds.

“[The] pH and mineral salt content can add flavors to vodka,” she explains. “It can also change mouthfeel, and therefore how you perceive the flavors and aromas.” For example, acidity can add a puckery feeling, while basic water can create a slippery sensation.

Mathias Tönnesson, master blender for Sweden’s Purity Vodka, credits “super soft water” brought to the distillery from a well in the middle of the country for “opening up flavor compounds… The softer the water, the more flavors you get,” he says.

By “soft,” he means it’s relatively free of minerals like magnesium and calcium, but does contain sodium—an important distinction.

“A pinch of salt enhances flavors,” Tönnesson says. “That opens up and enhances the overall flavor experience.” Further, the water “indirectly adds softness and smoothness,” he adds.

To create vodka with distinctions Tönnesson says, you need water with some character.

“Most vodka uses reverse osmosis to clean the water,” he explains. “You delete everything that’s not water, it’s very bland. Industrial distillers will try to take away flavors. Then, maybe, water doesn’t matter.”

More Than MarketingIn terms of vodka specifically, Scott traces the importance of water sourcing back to the “vodka wars” of the late 1990s.

“With so many brands in the market, it became a point of differentiation,” he recalls. At first, many producers pointed to the base raw materials—i.e. vodkas made from corn, or from potatoes. As the market became more saturated, some brands started to flaunt the origins of their water, the other big ingredient in the bottle. “It’s 60% of the product, it does make a difference in your final product,” Scott notes.

While it’s tempting to dismiss water provenance as little more than a marketing ploy, vodka producers began to talk more about a sense of place, likening it to the wine industry’s emphasis on terroir. Water sources fit right into the discussion.

WHERE’S YOUR VODKA FROM? IT’S COMPLICATED.

“It got stronger in the early 2000s and kept right on going,” Scott says. “I don’t see it going away, either.”

Tönnesson agrees, “It adds a local element.” He notes that this is already a practice in some whiskey distilleries—like Kentucky bourbon makers leaning on limestone-rich water. “You want to create a local play of saying, we are from this part [of the world] and therefore we take water from this well or spring close to this distillery.”

Others say specifying where water comes from adds an element of transparency.

“It’s marketing—but it’s not just marketing,” Bartlemay says. “It’s a way to talk about your branding and the romance, the sense of the place where you’re from. But the source also matters as a way of being transparent—‘glacier-fed spring water’—all those words mean something. By calling out the source, it shows that you’re trying to source quality ingredients, and you’re confident about where it comes from.”

Scott agrees, adding, “Water differs from place to place. Some of it’s better, some of it’s different.” Specifying a local origin might help consumers to understand why a brand is different from others, “but being able to back that up with fact is important.”