Water is the biggest ingredient in beer by far, yet it is often the last one brewers learn to control. The minerals dissolved in brewing water affect enzyme activity, hop perception, malt character and even colour. Long before anyone could measure them, these minerals quietly shaped the classic beer styles of Europe.
The Key Players
Brewers track a handful of ions, usually measured in parts per million (ppm, equivalent to mg/L):
- Calcium (Ca²⁺) — The brewer’s best friend. Lowers mash pH, helps enzymes, aids yeast flocculation and beer clarity. Around 50–150 ppm suits most styles.
- Magnesium (Mg²⁺) — A yeast nutrient in small amounts. Too much tastes sour-bitter and can be laxative.
- Sodium (Na⁺) — Rounds out malt flavour at low levels; tastes salty at high levels.
- Sulfate (SO₄²⁻) — Accentuates hop bitterness, giving a drier, crisper finish.
- Chloride (Cl⁻) — Enhances fullness and malt sweetness.
- Bicarbonate (HCO₃⁻) — Raises alkalinity, resisting drops in mash pH. Useful with dark, acidic malts; troublesome with pale beers.
Mash pH: Why It Matters
Mash enzymes work best at a pH of roughly 5.2–5.6 (measured at room temperature). Pale malts alone tend to leave the mash a little high in pH, while dark roasted malts are acidic and pull it down. Water chemistry is how brewers land in the sweet spot:
- Pale beers generally want low alkalinity
- Dark beers can tolerate or even need more alkalinity
Getting pH right improves efficiency, clarity, stability and flavour.
Sulfate-to-Chloride Ratio
A popular shorthand for flavour balance:
- High sulfate:chloride (e.g. 3:1) — dry, crisp, hop-forward; great for IPAs
- Balanced (around 1:1) — rounded, all-purpose
- High chloride:sulfate — soft, full, malty; favoured in hazy IPAs and malty lagers
It is a useful guide, not a law — the absolute amounts matter too.
Four Famous Water Profiles
| Ion (ppm, approx.) | Plzeň | Munich | Dublin | Burton-on-Trent |
|---|---|---|---|---|
| Calcium | 7–10 | 75–80 | 115–120 | 270–350 |
| Magnesium | 2–3 | 18–20 | 4–5 | 40–60 |
| Sodium | 2–3 | 2–10 | 12 | 25–55 |
| Sulfate | 5–8 | 5–10 | 55 | 600–800 |
| Chloride | 5 | 2–5 | 19 | 35–60 |
| Bicarbonate | 15 | 150–300 | 200–320 | 140–300 |
| Classic styles | Czech Pilsner | Dunkel, Helles, Bock | Dry Stout | English Pale Ale, IPA |
Published figures vary widely depending on the source and era, and many historic breweries treated their water, so treat these as illustrative rather than exact.
Plzeň (Pilsen), Czech Republic
Extremely soft water with almost no minerals. It lets delicate Pilsner malt and Saaz hops shine, producing a smooth, rounded bitterness rather than a sharp one. The original Pilsner of 1842 owes much to this water.
Munich, Germany
Moderately hard with significant bicarbonate. That alkalinity suited darker malts, which is one reason Munich was famous for dark lagers like Dunkel long before pale Helles emerged. Brewers later learned to treat the water to make paler beers.
Dublin, Ireland
High in bicarbonate and alkalinity. Acidic roasted barley balances that alkalinity perfectly, helping explain why Dublin became synonymous with dry stout.
Burton-on-Trent, England
Famously hard, packed with calcium sulfate (gypsum) from the local geology. The high sulfate gives a firm, dry, lingering bitterness. Burton pale ales were so admired that brewers elsewhere began adding gypsum to their water — a practice called Burtonisation.
Adjusting Your Water
You do not need to live in Burton to brew a Burton ale. Start by getting a water report from your supplier or a lab, then adjust:
- Gypsum (calcium sulfate) — adds calcium and sulfate
- Calcium chloride — adds calcium and chloride
- Epsom salt (magnesium sulfate) — adds magnesium and sulfate, use sparingly
- Lactic or phosphoric acid — lowers alkalinity and mash pH
- Reverse osmosis (RO) or distilled water — a blank slate to build any profile
Free online water calculators help predict the results.
Chlorine and Chloramine
Many municipal supplies are disinfected with chlorine or chloramine, which can create medicinal, plastic-like chlorophenols in beer. Remove them with a carbon filter or a small dose of Campden tablets (potassium or sodium metabisulfite) before brewing.
Safety Note
Only use food-grade brewing salts and acids, measure carefully, and handle concentrated acids with gloves and eye protection. Small additions go a long way — it is easy to overshoot.
Key Takeaways
- Calcium, sulfate, chloride and bicarbonate matter most
- Aim for a mash pH around 5.2–5.6
- Sulfate sharpens hops; chloride softens and fills out malt
- Historic water profiles shaped historic styles — and you can recreate them