Coffee Water Chemistry · No. 01
The Water Bench
Hardness and alkalinity are two separate variables, not one blurry "water quality" — this tool doses them independently, using the same mineral salts specialty roasters and cafés use. Get a real recipe, not just a filter recommendation.
Your starting water
Test strips and utility reports usually give you Total Hardness and Alkalinity, both "as CaCO₃." Enter those — the tool splits them into actual calcium, magnesium and bicarbonate.
Target profile
SCA is the published reference standard. The other two are heuristic, brewing-community profiles — not official standards — for comparison.
Batch & stock solutions
Milligram doses aren't kitchen-measurable, so you pre-dissolve each mineral into a stock solution and dose that by the millilitre instead.
grams of salt dissolved into mL of distilled water (default 5 g / 500 mL — do this separately for each of the three minerals).
How this is calculated
Each salt is chosen to isolate one ion so the three don't chemically interact in unwanted ways. Dose (g) = (target ppm − current ppm) × litres ÷ (active fraction × 1000).
| Salt | Molar mass | Active ion fraction |
|---|---|---|
| Calcium chloride dihydrate | 147.02 g/mol | Ca — 27.3% |
| Epsom salt (MgSO₄·7H₂O) | 246.47 g/mol | Mg — 9.9% |
| Baking soda (NaHCO₃) | 84.01 g/mol | HCO₃ — 72.6% |
Hardness/alkalinity "as CaCO₃" are converted to actual ion ppm using standard equivalent-weight ratios (Ca ×0.4, Mg ×0.243, HCO₃ ×1.219), then split into Ca/Mg by the slider ratio above.
Your recipe
Live, updates as you type
What you'll need
Food-grade only — these are the same three salts used in the calculation above, plus the two tools that make dosing practical at home.
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