Bottled waters differ by an order of magnitude in mineral content, and the label tells you everything.
What to look for
Bicarbonate (HCO₃⁻) — the key number. Under 50 mg/L is good; under 30 is better. This is alkalinity, and it flattens acidity.
Calcium + magnesium — combined, giving hardness. Moderate is what you want, roughly 20 to 50 mg/L calcium.
Total dissolved solids — 75 to 250 mg/L.
Sodium — low. Sodium contributes nothing useful to extraction.
What to avoid
High-mineral waters — some brands run 300 to 400 mg/L bicarbonate. Excellent as drinking water, poor for coffee, and they will scale a machine quickly.
Distilled or “pure” waters with essentially zero minerals. Coffee brewed in them is hollow and empty.
Reading the label
European mineral waters print their mineral analysis on the label, usually in mg/L; many US brands publish it in an annual water quality report on their website. Compare the bicarbonate figure across a few brands and the differences are startling.
The practical approach
Buy three bottles with different profiles, brew the same coffee in each, and taste them side by side.
One will be clearly better, and it will usually be the one with the lowest bicarbonate.
The cost
Bottled water for daily brewing is expensive and generates a lot of plastic. It is a good way to learn what profile you like, then reproduce it with a filter or a recipe.
Last reviewed 30 October 2026