Water Chemistry for Brewing: A Simple Adjustment Guide
Brewing water comes down to three jobs: remove chlorine, hit your mash pH, and set the sulfate-to-chloride balance for the style. Here is what each mineral does, how much each salt adds, and target profiles for the beers you brew most.
In this post
The short answer: brewing water comes down to three jobs. Remove chlorine and chloramine, get your mash pH into the 5.2 to 5.6 range, and set the balance of sulfate to chloride for the style you are brewing. Everything else is fine-tuning. If you want the simplest route to full control, start from reverse osmosis (RO) or distilled water and add salts back.
This guide explains what each mineral does, how much each brewing salt adds, and target water profiles by style, followed by a step-by-step adjustment routine you can use on every brew day.
Step 1: Remove chlorine and chloramine
Most city water is disinfected with chlorine or chloramine. Both react with compounds from malt to form chlorophenols, which taste medicinal, like plasters or mouthwash, even at tiny levels. This is the one water fix every brewer should make.
- Campden tablets (potassium or sodium metabisulfite): one tablet treats about 20 gallons of water in a couple of minutes and removes both chlorine and chloramine.
- A carbon filter removes chlorine easily and chloramine if the water flows through slowly.
- RO or distilled water has neither.
Boiling or leaving water to stand overnight removes chlorine but not chloramine, so do not rely on it.
What each mineral does
| Ion | Typical brewing range | What it does | Too much |
|---|---|---|---|
| Calcium (Ca) | 50 to 150 ppm | Lowers mash pH, helps enzymes and yeast, improves clarity | Rarely a problem below 200 ppm |
| Magnesium (Mg) | 5 to 30 ppm | Yeast nutrient; malt already supplies most of what yeast need | Sour, bitter or laxative above about 40 ppm |
| Sodium (Na) | 0 to 100 ppm | Rounds out malt flavour in small amounts | Salty, harsh above about 150 ppm |
| Chloride (Cl) | 50 to 150 ppm (up to 200 for hazy IPA) | Fuller, softer, rounder malt character | Heavy, flabby above about 250 ppm |
| Sulfate (SO₄) | 50 to 350 ppm | Drier finish, crisper and firmer hop bitterness | Harsh, minerally bitterness |
| Bicarbonate (HCO₃) / alkalinity | 0 to 50 ppm for pale beers; 100 to 200+ for dark beers | Raises mash pH; balances the acidity of dark roasted malts | Mash pH too high in pale beers: dull, harsh, astringent |
The sulfate-to-chloride ratio
Sulfate and chloride pull a beer in opposite directions. Sulfate makes it drier and more bitter; chloride makes it fuller and maltier. The ratio between them is the quickest way to steer a beer's balance:
| SO₄ : Cl ratio | Effect | Good for |
|---|---|---|
| 3:1 or higher | Very dry, sharp bitterness | West Coast IPA, double IPA |
| 2:1 | Crisp, hop-forward | Pale ale, bitter, German pils |
| 1:1 | Balanced | Amber ale, most lagers, brown ale |
| 1:2 | Round, malty, soft | Stout, porter, Scotch ale, märzen |
| 1:2 to 1:3 | Soft, full, juicy | Hazy (New England) IPA |
The ratio only matters when both numbers are in a sensible range. 20 ppm of sulfate and 10 ppm of chloride is technically 2:1, but it is too little of either to taste.
Brewing salts: what they add
These are the additions most brewers use. Amounts are per US gallon of water.
| Salt | 1 gram per gallon adds | Use it to |
|---|---|---|
| Gypsum (calcium sulfate) | about 62 ppm calcium, 147 ppm sulfate | Dry out and sharpen hoppy beers |
| Calcium chloride | about 72 ppm calcium, 127 ppm chloride | Soften and fill out malty beers |
| Epsom salt (magnesium sulfate) | about 26 ppm magnesium, 103 ppm sulfate | Add sulfate without more calcium; use sparingly |
| Table salt (non-iodized sodium chloride) | about 104 ppm sodium, 160 ppm chloride | A touch of roundness; small amounts only |
| Baking soda (sodium bicarbonate) | about 72 ppm sodium, 191 ppm bicarbonate | Raise alkalinity for dark beers on soft water |
| Lactic or phosphoric acid | No minerals of note | Lower mash and sparge pH |
Chalk (calcium carbonate) appears in old recipes but barely dissolves in water, so it is unreliable. Use baking soda or pickling lime if you need to raise alkalinity.
Target water profiles by style
| Style | Calcium | Sulfate | Chloride | Alkalinity |
|---|---|---|---|---|
| Pilsner, helles, kölsch (soft) | 40 to 60 | 40 to 70 | 40 to 60 | Very low |
| Pale ale, West Coast IPA | 100 to 150 | 200 to 300 | 40 to 75 | Low |
| Hazy IPA | 100 to 150 | 75 to 150 | 150 to 200 | Low |
| Amber, brown ale, most lagers | 75 to 100 | 75 to 125 | 75 to 125 | Low to moderate |
| Stout, porter | 50 to 100 | 50 to 75 | 75 to 125 | Moderate to high |
All figures in ppm (mg/L). These are sensible starting points, not rules. Adjust by taste over a few batches.
Classic brewing cities show the idea in action. Plzeň's very soft water made the first pale, hoppy lager possible (see our pilsner vs lager guide). Burton-on-Trent's sulfate-heavy water made crisp, bitter pale ales, and Dublin's high alkalinity suited dark stouts.
How to adjust your water, step by step
- Know your starting water. Get a water report from your city (ask for calcium, magnesium, sodium, chloride, sulfate and alkalinity or bicarbonate), send a sample to a lab, or skip this step by starting with RO or distilled water, which is close to zero on everything.
- Remove chlorine and chloramine with a Campden tablet or carbon filter.
- Pick a target profile for the style from the table above.
- Calculate additions with a brewing water calculator. Most brewing software has one built in. Enter your starting water, volumes and grain bill; it gives you grams of each salt and an estimated mash pH.
- Add the salts to the mash and sparge water in proportion to their volumes. On an all-in-one system, such as the Unibräu, you can simply treat the full water volume before you heat it.
- Check mash pH about 15 minutes after mashing in, with the sample cooled to room temperature. Aim for 5.2 to 5.6 and adjust with lactic acid if it is high. Our mash pH guide covers this step in detail.
- Write it down. Once a recipe tastes right, the same additions will give you the same beer every time.
Frequently asked questions
Do I need to adjust my brewing water?
Always remove chlorine and chloramine. Beyond that, if your tap water tastes good and your beers taste good, you may not need to do much. Water adjustment matters most for very pale beers, very hoppy beers, and when your mash pH is out of range.
Can I brew with tap water?
Yes, once it is treated for chlorine and chloramine. Most tap water makes decent beer. Very hard or alkaline tap water is harder to brew pale styles with; diluting it with RO water is the easiest fix.
RO or distilled water: which is better?
Both work as a blank slate. RO is cheaper in bulk and easy to get from a water store or an under-sink unit. Do not brew with pure RO or distilled water without adding minerals back; yeast and enzymes need calcium.
Should I add salts to the mash or the boil?
Mostly to the mash and sparge water, because calcium and alkalinity affect mash pH. Some brewers add part of the gypsum or calcium chloride to the boil to fine-tune flavour without moving mash pH.
What does ppm mean?
Parts per million, the same as milligrams per litre (mg/L). 100 ppm of calcium is 100 mg of calcium in every litre of water.
Does water really change how beer tastes?
Yes. The same recipe brewed with high-sulfate and high-chloride water tastes noticeably different: one crisp and bitter, the other soft and full. Water is also the most common hidden cause of harsh bitterness, dull flavour and medicinal off-flavours.