Water Alkalinity & Coffee
Why alkalinity matters for perceived acidity and why hardness and alkalinity should not be treated as the same measurement.
Alkalinity is not hardness
Hardness concerns mainly calcium and magnesium; alkalinity describes the water's acid-neutralising capacity. They can be related in natural waters but are chemically distinct.
Acid buffering
Alkalinity can buffer acids extracted from coffee. This can affect perceived brightness and the balance between acidity and other flavours.
Carbonate chemistry
Bicarbonate is a common contributor to alkalinity in drinking water. The exact chemistry depends on pH, dissolved carbon dioxide and the mineral composition of the source water.
Why this matters
Two waters with similar hardness can behave differently in coffee if their alkalinity differs substantially.
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