Water chemistry — a practical introduction
Why brewing water matters, how to read a water report, and target profiles for the styles most homebrewers attempt first.
Last updated 22 March 2026 · 12 min read
Why this matters
Beer is roughly 95% water by weight. The mineral content of that water — calcium, magnesium, sodium, sulphate, chloride, bicarbonate — affects mash pH, hop bitterness perception, malt sweetness perception, and yeast health. You don’t have to micromanage it, but you should at least know what’s in your tap.
The six ions to know
| Ion | Effect | Useful range (ppm) |
|---|---|---|
| Calcium (Ca²⁺) | Drops mash pH, helps yeast flocculate | 50–150 |
| Magnesium (Mg²⁺) | Yeast nutrient; harsh above ~30 | 10–30 |
| Sodium (Na⁺) | Accentuates malt sweetness; harsh above ~150 | 0–100 |
| Sulphate (SO₄²⁻) | Drying, accentuates hop bitterness | 50–350 |
| Chloride (Cl⁻) | Fullness, accentuates malt | 50–250 |
| Bicarbonate (HCO₃⁻) | Raises mash pH; problematic for pale beers above ~50 | 0–250 |
Target profiles for common styles
| Style | Ca | Mg | Na | SO₄ | Cl | HCO₃ |
|---|---|---|---|---|---|---|
| Bohemian Pilsner | 30 | 5 | 5 | 10 | 5 | 0 |
| German Pilsner | 50 | 10 | 5 | 70 | 60 | 25 |
| American IPA | 100 | 10 | 25 | 250 | 50 | 50 |
| Irish Dry Stout | 110 | 20 | 25 | 60 | 70 | 220 |
| British Bitter | 90 | 20 | 50 | 250 | 60 | 100 |
(These are approximate targets; minor variation has minor effects.)
What to do in practice
- Get a water report from your supplier, or pay £25 for a private water test. Most UK municipal water is fine for most styles with minor adjustments.
- For very pale or hop-forward beers, consider diluting with reverse-osmosis water to bring bicarbonate down.
- Add brewing salts to hit a profile. Calcium sulphate (gypsum) for hop-forward beers, calcium chloride for malty beers, table salt sparingly for fullness.
A spreadsheet or one of the various water-chemistry calculators makes the math trivial; the value is in knowing what you’re solving for.