What Water to Use for Pour-Over Coffee? Does Purified Water Make Coffee Sour? Can You Use Mineral Water for Coffee?

Perhaps you're using high-quality coffee beans with the right brewing parameters and techniques, but you still notice some undesirable flavors in your coffee. In that case, the problem might be with your water.

You might say, "Water is colorless and tasteless, so if it meets drinking standards, isn't it all the same?" You might be overlooking the presence of minerals. In non-pure water (distilled water), there are always some calcium ions, magnesium ions, and bicarbonate ions. The scale that forms when boiling water is clear evidence of this. The amount of these substances determines the water's hardness.

Let's start with some key insights: Christopher H. Hendon, a chemistry expert from MIT, stated in "Water for Coffee": "Water can change the character of coffee."

Water itself contains many substances. Higher levels of magnesium and calcium ions make water harder. The key point is that minerals in water have adsorptive properties. When water comes into contact with coffee grounds, these substances will adsorb compounds from the coffee. For example, the more eugenol the water adsorbs, the woodier the coffee will taste.

Among these, magnesium ions have particularly strong adsorptive power. Therefore, water with higher magnesium content typically makes coffee taste stronger (and with higher caffeine content). At the same time, harder water also contains more carbonates, and Hendon found that these substances make coffee more bitter.

Therefore, while magnesium ions help with coffee extraction, you cannot control the content of substances in water. As magnesium ions increase, other substances also increase. Water that is too hard is not suitable for brewing coffee as it will make a cup of coffee bitter.

The Role of Pure Water

So, pure water (0ppm) contains no substances—surely it can be used to brew coffee! According to Hendon, [this is even worse]. Because 0ppm water contains no substances, its extraction efficiency actually decreases. Coffee brewed with pure water often tastes thin.

Ideal Water for Coffee Brewing

Therefore, water suitable for brewing coffee should contain magnesium ions, calcium ions, and other substances, but not in excess. In the SCA's "Professional Barista's Handbook," the recommended TDS for water is 120-130ppm. In "Water for Coffee," the water standards provided by the Specialty Coffee Association of America show that water with TDS values between 75-250ppm is suitable for brewing coffee.

This is why in many major brewing competitions, contestants often mention that they prepare their own water when introducing their brewing parameters. They aim to use water with appropriate levels of magnesium and calcium ions to help extract coffee with rich flavors.

We rarely encounter knowledge about water preparation, nor do we need to spend too much effort making it. So what waters are suitable for brewing coffee in reality? You can refer to mineral water available on the market. Mineral water labels will indicate the content of various substances and the TDS value. Everyone can refer to the 75ppm value when making purchases. FrontStreet Coffee currently uses Nongfu Spring from Qiandao Lake water source, with a TDS value around 50ppm.

As for whether filtered water from home filters can be used for brewing coffee, different home filtration systems have varying effects on water filtration. You need to test the TDS of your filtered water to see if it falls within the 75-250ppm range.

Important Notice :

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