Water chart
Enter the hardness and alkalinity of your water, or a bottle label: see where it sits against published targets and which treatment would help.
Or pick a sample water
Water chart
ppm as CaCO₃
Key and notes
Key: amber box = SCA 2018 range (hardness 50–175, alkalinity 40–75 ppm) · black square on thin bar = SCAA 2009 target, calcium hardness 68 at alkalinity 40 (bar: acceptable calcium hardness 17–85); the SCAA standard gives calcium hardness, not total hardness, so it is not directly comparable on this axis · hatched = corrosion risk (alkalinity below 40; hardness above 1.8 × alkalinity) · dotted line = hardness equals alkalinity (limestone) · dashed line = 150 ppm alkalinity, up to which espresso shows no clear buffering.
Treatment directions: ↓ softener · ↙ decarboniser · towards zero: reverse osmosis + blending · ← dealkaliser · ↑ hardener · ↗ carboniser · → alkaliser (bicarbonate). Hover an arrow for its name.
Arrows show the direction each treatment moves a water, not how far. Amber arrows move this water towards the SCA range. Sample waters are worked examples from the SCA handbook.
How it works, the formulas and all sources: Water for coffee.