Water for Coffee

A cup of coffee is about 98% water, so the water you brew with matters almost as much as the beans. Two things make the difference: temperature and mineral content.

Temperature

The sweet spot for most brewing is 90–96°C — just off the boil. Too hot and you scorch the coffee into bitterness; too cool and you under-extract into sourness. As a rule of thumb, use hotter water (94–96°C) for lighter roasts, which are denser and harder to extract, and slightly cooler water (90–93°C) for darker roasts, which give up their flavour more easily. Boiling the kettle and letting it rest for 30–45 seconds lands you in range.

Mineral content

Minerals in water — chiefly magnesium and calcium — bind to and carry coffee flavour. Water that's too soft tastes flat; water that's too hard tastes dull and chalky, and furs up your kettle. Most filtered tap water sits in a good range. If yours is very hard or heavily chlorinated, a simple filter jug noticeably improves the cup. Avoid distilled or zero-mineral water — it extracts poorly and tastes empty.

The simple version

Use fresh, filtered water, just off the boil, and you're most of the way there. Our brew guides give the exact temperature for each method.