Encyclopedia Category
Water Chemistry for Coffee
Water makes up roughly 98 percent of brewed coffee, so its chemistry has enormous impact on flavor. Minerals like calcium and magnesium drive extraction, while bicarbonate buffers acidity. This category explains hardness, alkalinity, and how to dial in water for better coffee.
Why Water Matters
Minerals in water pull flavor compounds out of coffee. Calcium and magnesium extract different compounds, so the mineral balance changes the cup. Too few minerals and the coffee tastes flat; too many and it tastes harsh.
Bicarbonate acts as a buffer, muting acidity. High alkalinity makes coffee taste dull; too little lets acidity run sharp and unbalanced.
Hardness and Alkalinity
General hardness measures calcium and magnesium; alkalinity measures bicarbonate. The SCA recommends roughly 150 mg/L total hardness and 40 mg/L alkalinity as a starting point.
Filtered or lightly mineralized water beats distilled water, which has no minerals to extract with, and hard tap water, which over-mineralizes the cup.
All Water Chemistry Articles
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Frequently Asked Questions
Why does water matter for coffee?
Water is about 98 percent of brewed coffee, and its minerals drive extraction. Too few minerals under-extract; too many taste harsh; the wrong balance mutes or sharpens acidity.
What is TDS in water for coffee?
TDS, or total dissolved solids, measures the mineral content of water. The SCA suggests around 150 mg/L total hardness and 40 mg/L alkalinity as a starting point.
Should I use filtered water for coffee?
Filtered or lightly remineralized water is ideal. Distilled water lacks minerals to extract with, and hard tap water can over-mineralize the cup.
What is the ideal water for espresso?
Espresso benefits from moderately hard water with balanced alkalinity, around the SCA recommendations, to extract fully without mutting acidity or scaling the machine.
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