Total hardness vs alkalinity
Understand the difference between total hardness and alkalinity, and how each affects extraction and flavor in coffee brewing.
- Coffee Basics Nerds
- 1 min read
Key Concepts
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Total Hardness:
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Measures the concentration of calcium (Ca²⁺) and magnesium (Mg²⁺) ions.
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Hardness affects flavor extraction, crema stability in espresso, and scale buildup in equipment.
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Alkalinity (Buffering Capacity):
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Ability of water to resist changes in pH, primarily from bicarbonate (HCO₃⁻) ions.
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High alkalinity can neutralize acids, resulting in muted brightness and flavor in coffee.
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Interactions:
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Optimal coffee brewing water balances moderate hardness and low-to-moderate alkalinity.
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Excessive hardness with low alkalinity can taste harsh; high alkalinity can flatten the cup.
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Practical Notes:
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Water testing kits or lab analysis can measure both parameters.
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Adjustments using salts or RO water blending help achieve ideal profiles.
Summary
Monitoring total hardness and alkalinity is critical for consistent coffee flavor and to prevent scaling in espresso machines or filter brewers.