The Impact of Water on Coffee

Water accounts for approximately 98% of a brewed coffee, signifying that water quality profoundly influences coffee flavor—far beyond what most people imagine. Although water is transparent and colorless, it still contains numerous minerals and organic compounds that are invisible to the naked eye.

Why Does Water Quality Matter?

In southern Taiwan, water is typically harder, containing higher levels of dissolved minerals. This produces coffee with a distinctly creamy, milky mouthfeel. Conversely, in northern Taiwan, softer water generally results in smoother coffees that clearly highlight fruity acidity. But why does this difference exist? Let’s delve deeper into the concepts of hard and soft water.

Understanding Hard vs. Soft Water

Water hardness is defined by the total mineral content dissolved in water, commonly measured as TDS (Total Dissolved Solids). TDS values are expressed in ppm (parts per million). According to the World Health Organization (WHO):

• Soft water: less than 60 ppm
• Moderately soft water: between 60–120 ppm
• Hard water: greater than 120 ppm

Higher water hardness generally results in a coffee that tastes more bitter and harsh. Conversely, softer water tends to yield coffee with brighter acidity and sweetness.

Ideal Water Standards for Brewing Coffee (SCA Guidelines)

The Specialty Coffee Association (SCA) provides water quality recommendations for optimal coffee brewing:

• Total Hardness (TDS): 50–175 ppm
• pH Level: Ideally between 6.5–7.5 (acceptable range: 6–8)

Adhering to these standards helps ensure the best extraction and flavor characteristics of the coffee.

Why We Often Overlook Water

When brewing coffee, most enthusiasts carefully consider:

• Coffee origin
• Roast level
• Coffee-to-water ratio
• Grind size

Yet, water—the critical component—is frequently overlooked. Recognizing the significance of water is essential because it significantly shapes the taste and quality of your cup of coffee.

Experimenting with Water

There's no universally "perfect" water for coffee. Whether you use tap water or filtered water, exploring different water qualities is insightful. Consider conducting blind taste tests with the same coffee beans and brewing methods but varying water types. First, taste blindly to get a sensory baseline, then compare your notes with measurable TDS or hardness data. Such experiments can vividly illustrate water’s substantial role in influencing coffee flavor profiles.