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

The Impact of Water on Coffee Flavor

As the primary raw material, water not only constitutes the vast majority of a cup of black coffee but also affects the extraction of different compounds, thereby presenting unique flavors and textures. Therefore, we should all understand the importance of water to coffee.

Common drinking water on the market varies widely—from brands to ingredients, from purification processes to intended uses—the variety can be dazzling. It is precisely because of these varying effects that people have become more curious and engaged in discussions. For instance, not long ago, a brewing enthusiast posed this question: "Does coffee brewed with the most expensive water taste better than that made with cheaper water?"

Although this question is ambiguous—after all, we cannot define what exactly constitutes "the most expensive water" and "the cheapest water"—FrontStreet Coffee always likes to adopt a trial mentality, never letting go of any topic worth writing about. So today, let's start exploring this confusion by "playing with water."

Considering that people typically prefer to use "large quantity and satisfying" bottled water for daily coffee brewing, the focus of this article remains on such products. FrontStreet Coffee directly opened a commonly used food delivery platform, selected the most expensive and cheapest bottled water, and finally identified two products: Kunlun Mountain Snow Mineral Water at 19.9 RMB/5L and Dinghu Mountain Spring Natural Drinking Water at 6.9 RMB/5L. (Although Evian water, with its outstanding price, garners more attention, its TDS value (489ppm) far exceeds the maximum TDS value suitable for coffee brewing, so it's not suitable for making coffee. FrontStreet Coffee will not include it in this discussion.)

During the experiment, FrontStreet Coffee will also compare with Nongfu Spring water used in their store, and brew with two coffee 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 coffee will be shuffled and tasted "blind" to see what flavor performances each exhibits.

First Round Experiment

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

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

Nongfu Spring: With citrus, sweet orange, and black tea flavors, exhibiting berry acidity at lower temperatures, smooth mouthfeel, and balanced sweet-sour-bitter profile; (TDS: 1.31)

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

Second Round Experiment

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

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

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

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

From the flavor performance of coffee brewed with these three water qualities, it can be seen that the "most expensive" water did not produce better-tasting coffee than the "cheapest" water. The coffee brewed with the "lowest-priced" Dinghu Mountain Spring drinking water showed more prominent acidity and lower body; Nongfu Spring produced coffee with relatively balanced overall flavor performance; while the "highest-priced" Kunlun Mountain mineral water not only had a sharp mouthfeel but also diminished some aromas, making the coffee lack layers.

What Factors in Water Affect Coffee Extraction?

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

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

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

After discussing pH levels, let's continue with water hardness. Water composition consists of numerous elements, but for coffee extraction, the most important are magnesium ions, calcium ions, and bicarbonates. Water containing appropriate amounts of calcium ions can better dissolve coffee's acidity, while water with suitable magnesium ion content can effectively enhance the release of sweetness and aroma in coffee. Therefore, to brew good-tasting coffee, water must contain appropriate amounts of calcium and magnesium ions. What people commonly call "hard water" essentially refers to water with too much magnesium and calcium content, which can easily lead to mixed bitter flavors and is therefore not suitable for brewing coffee.

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 called hard water. For coffee brewing water, SCA suggests a range of 75-250 ppm, with an ideal value of 150ppm, but in practice, water with TDS below 100ppm is more likely to produce good-tasting flavors.

When FrontStreet Coffee used a TDS testing pen to measure the three types of water above, they found that Dinghu Mountain Spring Natural Drinking Water measured 25ppm TDS, containing the least magnesium and calcium ions; Nongfu Spring showed 37ppm TDS, with moderate calcium and magnesium ion content; while Kunlun Mountain Mineral Water measured 322ppm, indicating it has the highest dissolved substance content. This affects its extraction ability after coffee water addition, thereby causing changes in sour, bitter, aromatic, and sweet flavors.

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