Water for Espresso: Taste and Scale

Find out how hard your tap water is. Many water utilities publish this, or you can buy inexpensive test strips. Hardness is usually given in parts per million (ppm) or grains per gallon.

For most people, a filter jug or an in-tank filter cartridge designed for espresso machines is enough. In very hard-water areas, consider bottled water with a moderate mineral content or a dedicated espresso water recipe.

Pure distilled or reverse-osmosis water lacks the minerals that extract flavor and may confuse machines that sense water levels electrically. Some minerality is good.

Follow your manufacturer’s guidance precisely. Some machines — particularly dual boilers and many E61 machines — should not be descaled with generic products. The best descaling is the one you never need, thanks to good water.