Brewing water
Pilsen water
Among the softest brewing water in the world, with almost no mineral content — the reason a heavily-hopped pale lager tastes rounded rather than harsh.
Pilsen, Czechia
Read this as a reconstruction. Figures are the widely-reproduced historical analysis, stored as a range because the underlying supply varied by well, by season and over time. Treat them as an indication of relative character, not as a specification to dose water against. The extremely low values here are the most-cited figures in brewing; the essential and reliable point is that the water is exceptionally soft, not that any individual number is exact.
Soft water also has a drawback that Bohemian brewing had to work around: with almost no calcium, mash pH sits higher than ideal. Decoction mashing and undermodified malt both help compensate, which is part of why those techniques persisted here.
Mineral content
| Ion | mg/l | What it does |
|---|---|---|
| Calcium (Ca²⁺) | 3–12 ppm | Lowers mash pH, supports enzyme and protein behaviour, aids yeast flocculation and clarity. Close to flavour-neutral itself. |
| Magnesium (Mg²⁺) | 1–4 ppm | A yeast nutrient in small amounts. Above roughly 30 mg/l it begins to read as sour or metallic. |
| Sodium (Na⁺) | 1–5 ppm | Rounds and accentuates sweetness at moderate levels. With high sulphate it turns harsh rather than full. |
| Chloride (Cl⁻) | 3–8 ppm | Tends to accentuate malt fullness, body and roundness. A tendency in perception, not an additive sweetness. |
| Sulphate (SO₄²⁻) | 3–8 ppm | Tends to accentuate hop bitterness and drive a drier finish. At high levels it reads as harsh and minerally rather than simply more bitter. |
| Bicarbonate (HCO₃⁻) | 10–25 ppm | The alkalinity that resists mash acidification. High bicarbonate needs dark, acidic malt to balance it — which is why alkaline-water cities brewed dark beer. |
Overall hardness: very soft. Balance: balanced (chloride:sulphate roughly 1.00:1). The ratio is a shorthand the trade finds useful for describing whether a water pushes a beer toward crispness or fullness. It is not a formula, and two waters with the same ratio at very different total concentrations do not behave alike.
Historical context
Very low mineral content means very little to accentuate bitterness. That is precisely why Czech pale lager can carry 35–45 IBU of Saaz and still taste soft and rounded — the same hopping rate over Burton water would be aggressive.
Styles associated with this water
Association, not causation. Brewers selected recipes that worked with the water available to them; the water did not design the beer.
Other water profiles
- Balanced reference profile — moderately hard, balanced.
- Burton-on-Trent water — very hard, strongly sulphate.
- Dortmund water — hard, sulphate leaning.
- Dublin water — hard, sulphate leaning.
- Edinburgh water — hard, sulphate leaning.
- London water — moderately hard, balanced.
- Munich water — moderately hard, balanced.
- Vienna water — hard, sulphate leaning.
Last reviewed 2026-08-15.