Water for Making Tea and Coffee

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About
Brewed tea and coffee are 95–98% water, so their quality is strongly influenced by the quality of the water used to make them. The off-flavors and disinfectant chlorine compounds of most tap waters are largely driven off by boiling. Very hard water, high in calcium and magnesium carbonates, has several undesirable effects: in coffee, these minerals slow flavor extraction, cloud the brew, clog the pipes in espresso machines and reduce the fine espresso foam; in tea, they cause the formation of a surface scum made up of precipitated calcium carbonate and phenolic aggregates. Softened water overextracts both coffee and tea and gives a salty flavor. And very pure distilled water gives a brew best described as flat, with a missing dimension of flavor.