Page index

Water can change mineral buildup inside a home espresso machine and the taste of the shot. Here's what two makers say and where hardness comes in.

GH, KH, TDS and ppm explained for beginners, with the USGS hardness classes and what makers' water guides do with these numbers.

Where to get a reliable hardness number for your home water: your supplier's report, the supplier itself, test strips and TDS meters, and what each tells you.

Limescale is a chalky mineral deposit. Here's what it's made of, how it forms, and what two espresso makers say it does inside a machine.

Two espresso makers give nearly opposite water advice. Here's what each one says to use and avoid, and how to find the rule for your own machine.

How often to descale and with what depends on your machine. Here's what two makers say, how cleaning differs from descaling, and where to check.

How tap, filtered, bottled, reverse osmosis, distilled and softened water differ, and what two espresso makers say about each type.