Water chemistry has a reputation for being the deep end of homebrewing, and some of that is earned — but most of what a homebrewer needs is a handful of ions, three of which matter far more than the rest, and a table of what each salt actually adds. This page is that. It stops deliberately short of telling you a mash pH, and the last section explains why that is the honest place to stop.
What does a water report actually tell you?
Six numbers do nearly all the work. Three are cations — calcium, magnesium, sodium — and three are anions: sulfate, chloride and bicarbonate. Your utility publishes them, usually as an annual report, and if you are on a well you send a sample away. Everything else on the sheet is either irrelevant to beer or a restatement of those six.
| What it is | Aim for | Why |
|---|---|---|
| Calcium (Ca²⁺) | 50–100 ppm | Ales; 40 ppm minimum. Yeast flocculation, enzyme support, clarity. |
| Magnesium (Mg²⁺) | 0–30 ppm | Above 40 ppm it turns harsh. |
| Sodium (Na⁺) | 0–60 ppm | Up to 150 is tolerated, but under 60 matches the historic brewing centers. |
| Sulfate (SO₄²⁻) | 0–150 ppm | Up to 350 only in a heavily hopped beer. |
| Chloride (Cl⁻) | 10–100 ppm | Lower the ceiling when sulfate is high, or the beer turns minerally. |
| Alkalinity (as CaCO₃) | 0–50 ppm | As CaCO₃. Low for pale beers; dark beers tolerate more. |
Target ranges as published by Bru'n Water, which is the most conservative and best-argued set in homebrewing. "ppm" and "mg/L" are the same thing.
Alkalinity is the one that is not like the others. The first five are flavor and process ions — you want them in a band. Alkalinity is a buffer: it resists the mash's natural drop in pH, which is why soft water makes pale beer easy and hard, alkaline water does not. It is also the one you cannot simply add your way out of, because removing alkalinity means acid, dilution, or a different water source.
The three that matter first
If you never learn the rest, learn these. Calcium is the workhorse — it supports mash enzymes, helps protein drop out in the boil, and helps yeast flocculate at the end. Bru'n Water puts the useful range at 50–100 ppm for ales with a floor around 40, and most brewing water problems that are not alkalinity are simply not enough calcium.
Sulfate and chloride are the flavor pair. Sulfate sharpens and dries bitterness — it is what makes a Burton pale ale taste like one. Chloride does the opposite: it rounds and fills out malt. Neither is a seasoning you can taste directly at brewing levels; they change how the rest of the beer reads.
Magnesium, sodium and bicarbonate are mostly constraints rather than tools — numbers to stay under rather than targets to hit. Magnesium turns harsh past about 30 ppm, sodium gets minerally alongside high sulfate, and bicarbonate is alkalinity by another name.
What each salt actually adds
This is arithmetic, not opinion: a salt dissolving contributes its ions in the proportion their atoms make up of the compound. Per gram, in a liter of water:
| Salt | Formula | Ca | Mg | Na | SO₄ | Cl | HCO₃ | CO₃ |
|---|---|---|---|---|---|---|---|---|
| Gypsum | CaSO₄·2H₂O | 233 | — | — | 558 | — | — | — |
| Calcium chloride | CaCl₂·2H₂O | 273 | — | — | — | 482 | — | — |
| Epsom salt | MgSO₄·7H₂O | — | 99 | — | 390 | — | — | — |
| Table salt | NaCl | — | — | 393 | — | 607 | — | — |
| Baking soda | NaHCO₃ | — | — | 274 | — | — | 726 | — |
| Chalk * | CaCO₃ | 400 | — | — | — | — | — | 600 |
ppm added per gram of salt per liter of water, computed from atomic masses by this site's engine and matching the published tables to a tenth of a ppm. For a gallon, divide by 3.79. * Chalk does not dissolve — see below.
A worked example, because the per-liter figures are easy to misapply: 5 g of gypsum in a 21 L batch adds 55 ppm of calcium and 133 ppm of sulfate. One gram per gallon is 61 ppm of calcium. Note what the table shows about gypsum: it brings 2.4 times as much sulfate as calcium, so you cannot use it to reach a calcium target without taking a large sulfate addition with it. If calcium is what you want, calcium chloride delivers more of it (273 ppm against gypsum's 233) and brings chloride instead.
The addition that does not work
Look at chalk in the table. On paper it is the strongest calcium source there — 400 ppm per gram per liter, ahead of every soluble salt on the list, the best of which manages 273. Nearly every beginner primer lists calcium carbonate as the way to raise alkalinity for a stout.
Calcium carbonate is close to insoluble in neutral or alkaline water, so the numbers in its row are what it would contribute if it dissolved, and it mostly does not — it sits in the bottom of the mash tun. Bru'n Water's testing is blunt about it: "even in the mash, chalk does not dissolve in significant quantity... the mash pH can only be increased by 0.2 units, no matter how high the chalk dosage is," and its advice is to avoid chalk entirely. If you need alkalinity, baking soda works — it dissolves completely and brings 726 ppm of bicarbonate per gram per liter — and the sodium it comes with is what limits the dose.
This is the reason the table has a computed column and a caveat rather than just a caveat. The gap between what the chemistry says and what actually happens is the whole lesson of water chemistry: the stoichiometry is exact and trivial, and the difficulty is entirely in what the mash does with it.
Is the sulfate-to-chloride ratio real?
Half the primers on this subject print a ratio table — 2:1 for hoppy, 1:2 for malty, 1:1 for balanced — as though the ratio were the setting. The ratio is scale-free and your beer is not. "2:1" is 40 ppm of sulfate against 20 of chloride, and it is equally 300 against 150. The first is a restrained, clean bitterness; the second is double Bru'n Water's normal sulfate ceiling of 150 ppm and will taste mineral and drying whatever the ratio says.
It is telling that Bru'n Water does not publish a predictive ratio at all. It warns instead about absolute levels — that high sulfate alongside high sodium or chloride "can produce harsh or minerally flavor". Use the ratio as a direction of travel if you like, but set the absolute numbers first: sulfate under 150 unless the beer is genuinely hop-forward, chloride in the 10–100 band, and let whatever ratio falls out of that be the ratio.
Why this page will not give you a mash pH
Because it cannot, honestly, and neither can anything else that only knows your water. Mash pH is set by a reaction between your water's alkalinity and the acidity of the grain — and Bru'n Water is explicit that "the acidity provided by various grain types is not proportional to the color they impart to the beer", which is exactly the shortcut most simple estimators take. Base malt, crystal, roast and acid malt all behave differently, and a predictor without your grain bill in it is guessing.
So the honest position is this. The ion additions above are exact and you can use them today. A mash pH estimate needs a proper model of the grain bill's acidity, and we would rather have no calculator than a confidently wrong one — the same reason this site prints two IBU formulas and two fermentation-heat constants rather than picking one and hiding the disagreement. If we build a salts calculator, it will include the grain bill, and until then a five-dollar pH meter and a reading fifteen minutes into the mash beats any estimate on the internet.
Where to start, if you have never touched your water
- Deal with chlorine first. It is not a water-chemistry question so much as a flavor emergency: chlorine and chloramine make plastic and band-aid flavors, and a crushed Campden tablet per 20 L removes both. Our off-flavors guide covers what it tastes like when you skip it.
- Find your report and read six numbers. That is a ten-minute job and it tells you whether you have a problem at all. Plenty of municipal water is fine for pale beer as it comes.
- Get calcium into the 50–100 ppm band, using calcium chloride or gypsum depending on whether the beer wants malt or bitterness. For most people this is the only addition that will ever matter.
- If your water is alkaline and you brew pale beer, dilute with distilled or RO water rather than trying to neutralize it. Cutting the water 50/50 halves the alkalinity, which is simpler and more predictable than any acid addition.
- Leave everything else alone until you have a beer you want to change, and then change one thing.
That ladder gets you most of the available improvement without a spreadsheet. The rest — matching historic profiles, chasing mash pH to two decimals — is real, but it is the last five percent, and it is worth far less than pitching enough yeast and holding your fermentation temperature.