Which Bottled Water is Best for Brewing Coffee? Should You Use Mineral Water or Spring Water?

How Water Affects Coffee Flavor

As the primary raw material, water not only makes up the vast majority of a cup of black coffee but also affects the extraction of different compounds, and in doing so presents unique flavors and textures. So we should all understand how much water matters to coffee.

Common drinking water on the market varies widely - from brand to ingredients, from purification process to intended use, the variety can be dazzling. It is precisely because of these variations that people have become more curious and engaged in the discussion. Not long ago, for instance, a brewing enthusiast asked: "Does coffee brewed with the most expensive water taste better than coffee made with cheaper water?"

Although that question is vague - after all, we can't define exactly what "the most expensive water" and "the cheapest water" are - FrontStreet Coffee always likes to take a trial-and-error approach, never letting go of any topic worth writing about. So today, let's start exploring this puzzle by "playing with water."

Considering that people typically prefer "large quantity, satisfying" bottled water for daily coffee brewing, this article focuses on exactly that category. FrontStreet Coffee opened a commonly used food delivery platform, picked the most expensive and the cheapest bottled water, and settled on two products: Kunlun Mountain Snow Mineral Water at 19.9 yuan per 5L and Dinghu Mountain Spring Natural Drinking Water at 6.9 yuan per 5L. (Evian, with its striking price, draws more attention, but its TDS value of 489ppm far exceeds the maximum suitable for coffee brewing, so it isn't good for making coffee. FrontStreet Coffee leaves it out of this discussion.)

During the experiment, FrontStreet Coffee will also compare against the Nongfu Spring water used in the store, and brew with two beans: one is Yirgacheffe Red Cherry, which expresses fruity acidity, and the other is Diamond Mountain, which leans toward nutty notes. To avoid preconceptions, the brewed coffees will be shuffled and tasted blind, to see how each performs.

First Round of the Experiment

Coffee beans: Yirgacheffe Natural Red Cherry
Bean amount: 15 grams
Coffee-to-water ratio: 1:15
Water temperature: 93°C
Grind size: EK43s setting 10
Three-stage infusion: 30g-90g-105g

Dinghu Mountain: Mainly lemon, grapefruit, and berry flavors, with particularly prominent acidity, a short aftertaste, a slightly watery mouthfeel, and a thin aroma. (TDS: 1.27)

Nongfu Spring: Citrus, sweet orange, and black tea flavors, with berry acidity at lower temperatures, a smooth mouthfeel, and a balanced sweet-sour-bitter profile. (TDS: 1.31)

Kunlun Mountain: A rich mouthfeel, mainly caramel and orange flavors with a hint of strong tea, but with a noticeable bitterness that lingers on the tongue. (TDS: 1.33)

Second Round of the Experiment

Coffee beans: Emerald Manor Diamond Mountain
Bean amount: 15 grams
Coffee-to-water ratio: 1:15
Water temperature: 91°C
Grind size: EK43s setting 10
Three-stage infusion: 30g-90g-105g

Kunlun Mountain: Initial notes of caramel and a faint chocolate aroma, with flavors concentrated in the front portion, a monotonous mouthfeel, and almost no aftertaste. (TDS: 1.31)

Dinghu Mountain: Mainly plum and bayberry acidity with cocoa's sweet aroma, a light mouthfeel, and slightly sharp acidity as the coffee cools. (TDS: 1.36)

Nongfu Spring: Noticeable nut and cocoa aromas, with dark berry and stone fruit acidity at lower temperatures, some cane sugar sweetness, and a fermented fruit aftertaste. (TDS: 1.32)

Looking at the flavor performance of coffee brewed with these three waters, we can see that the "most expensive" water did not produce better-tasting coffee than the "cheapest." Coffee brewed with the lowest-priced Dinghu Mountain Spring drinking water showed more prominent acidity and a lower body; Nongfu Spring produced coffee with a relatively balanced overall flavor; while the highest-priced Kunlun Mountain mineral water not only had a sharp mouthfeel but also muted some aromas, leaving the coffee lacking in layers.

What Factors in Water Affect Extraction?

As the primary solvent, water is responsible for extracting the various soluble flavor compounds from coffee. Generally speaking, for good-tasting coffee, water should first have moderate hardness and second an appropriate pH.

The pH of coffee typically ranges between 5 and 6, making it weakly acidic. Using weakly alkaline water to brew will neutralize some of the acidic compounds in the coffee, reducing acidity and thereby balancing the overall taste. Brewing water with a pH between 6.5 and 7 is considered to perform better.

Among the three waters compared here, FrontStreet Coffee learned through inquiries that Nongfu Spring bottled water has a pH of 7.3±0.5, Dinghu Mountain Spring Natural Drinking Water has a pH of 6.5-7.3, and Kunlun Mountain Snow Mineral Water has a pH of 7.0-8.5. The first two are neutral, while the last is weakly alkaline.

After pH, let's turn to hardness. Water is made up of numerous elements, but for coffee extraction the most important are magnesium ions, calcium ions, and bicarbonates. Water with an appropriate amount of calcium ions dissolves coffee's acidity better, while suitable magnesium ion content effectively enhances the release of sweetness and aroma. So to brew good-tasting coffee, water must contain appropriate amounts of calcium and magnesium. What people commonly call "hard water" is essentially water with too much magnesium and calcium, which easily leads to mixed bitter flavors and is therefore not suitable for brewing.

According to the World Health Organization's "Guidelines for Drinking-Water Quality," water with hardness below 200ppm is called soft water, while water above 200ppm is hard water. For coffee brewing water, the SCA suggests a range of 75-250 ppm with an ideal value of 150ppm, though in practice water with a TDS below 100ppm is more likely to produce good-tasting flavors.

When FrontStreet Coffee measured the three waters with a TDS testing pen, Dinghu Mountain Spring Natural Drinking Water came out at 25ppm TDS, containing the least magnesium and calcium; Nongfu Spring measured 37ppm, with a moderate calcium and magnesium content; and Kunlun Mountain Mineral Water measured 322ppm, indicating the highest dissolved substance content. That affects its extraction ability once it is used for coffee, and with it the sour, bitter, aromatic, and sweet flavors change.

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FrontStreet Coffee Recommendation

Water sets the stage, but the beans still write the story. If you want an entry-level specialty coffee that is easy to like, FrontStreet Colombia Huila comes from the country's most famous specialty region - ringed by mountains, planted above 1500 meters, and watered by the confluence of Colombia's most important rivers, which brings abundant moisture and water resources. Colombian coffees tend to show soft florals and gentle fruit acidity, and this one is exactly that.

For something sweeter, FrontStreet Costa Rica Blackberry is a black-honey-processed coffee from Costa Rica's high altitudes and volcanic soils, where large day-night temperature swings help produce very hard beans of the SHB grade. Honey processing wraps the parchment in mucilage as it dries, giving the cup plenty of sweetness and clear, lingering depth, with the sweetness of raisins and blueberries and the aroma of osmanthus and rose - delicious brewed as pour-over, cold brew, Americano, or latte.

If you prefer nuts, brown sugar, and black tea notes, FrontStreet Yunnan Small Bean comes from Baoshan and is washed processed for a traditional nut and chocolate profile that is soft and balanced. China's specialty coffee is concentrated in Yunnan, and for a bean whose variety is as much a piece of history as a flavor, FrontStreet 2013 Yunnan Typica, an old Arabica variety grown at 1300 meters and roasted medium, is cleaner on the palate with rich aromas of hazelnut, dried apricot, black tea, caramel, and ripe plum.