Cologne (Köln), Germany. Hard water with high residual alkalinity - suited to dark, roasty beers, with sulfate and chloride roughly in balance.
| Ion | ppm |
|---|---|
| Calcium (Ca²⁺) | 88 |
| Magnesium (Mg²⁺) | 14 |
| Sodium (Na⁺) | 20 |
| Chloride (Cl⁻) | 32 |
| Sulfate (SO₄²⁻) | 61 |
| Bicarbonate (HCO₃⁻) | 250 |
| Brewing numbers | |
|---|---|
| Total hardness (as CaCO₃) | 277.4 ppm |
| Alkalinity (as CaCO₃) | 205 ppm |
| Residual alkalinity (as CaCO₃) | 134 ppm |
| Sulfate-to-chloride ratio | 1.9:1 |
Salts to add to reverse-osmosis or distilled water, calculated by the BrewWaterSolver solver with the most common homebrew salts.
| Salt | 5 gal (18.9 L) | 20 L |
|---|---|---|
| Calcium chloride (CaCl₂) | 1.14 g | 1.20 g |
| Gypsum (CaSO₄) | 0.28 g | 0.30 g |
| Epsom salt (MgSO₄) | 2.50 g | 2.65 g |
| Chalk (CaCO₃) | 3.13 g | 3.30 g |
| Baking soda (NaHCO₃) | 1.18 g | 1.25 g |
The common salts reproduce every ion within 10%.
Chalk (CaCO₃) doesn't dissolve well directly in mash or sparge water without dissolved CO₂ - slurry it in carbonated water (e.g. sparkling water) before adding it, rather than mixing it into still water or sprinkling it in dry, or the calculated amount may not fully dissolve. How to dissolve chalk with CO₂
Cologne's municipal water, RheinEnergie right-bank supply (Höhenhaus/Zündorf): Ca 88, Mg 14, Na 20, Cl 32, SO4 61, 15.6 °dH; the left-bank supply is harder (Ca 106, Na 35, Cl 58, SO4 73). Bicarbonate isn't in the published summary - 250 is estimated from the ion balance. Kölsch brewers soften this moderately hard, alkaline water; for brewing Kölsch use the modern Kölsch target instead.