Water Chemistry & Adjustments
Ions, alkalinity, mash pH, chloride:sulfate balance, and how to use the Brewfather Water Calculator for consistent results
Water is often called the "silent ingredient" in beer — it affects nearly every quality dimension, from enzyme activity during the mash to hop perception in the glass. This page covers the science behind water adjustment, practical targets, and how to execute adjustments using Brewfather.
Why Water Chemistry Matters
The mineral content of your water influences:
Mash pH: Enzymes that convert starch to sugar operate optimally at pH 5.2–5.6. Outside this range, conversion efficiency drops, wort quality suffers, and off-flavors increase.
Flavor balance: Sulfate accentuates hop dryness and bitterness; chloride emphasizes malt roundness and fullness.
Yeast health: Calcium is essential for yeast flocculation and enzyme function.
Clarity and stability: Adequate calcium promotes precipitation of proteins and oxalate, reducing haze.
Overall flavor quality: Sodium adds roundness; magnesium can be harsh at high levels; excess alkalinity creates harsh, astringent wort from dark malts.
Key Ions and Their Effects
Calcium (Ca²⁺)
Calcium is the single most important brewing ion. It:
Lowers mash pH by precipitating phosphates from malt (releasing H⁺ ions).
Supports enzyme activity and yeast health (required cofactor for many enzymatic reactions).
Promotes protein and calcium oxalate precipitation (improves clarity and reduces gushing risk).
Enhances hop bitterness perception and reduces rounding.
Target range: 50–150 ppm. A minimum of 50 ppm is strongly recommended; 100–150 ppm is typical for most styles. Very high levels (>200 ppm) can taste chalky.
Sources: Gypsum (CaSO₄) adds Ca²⁺ and SO₄²⁻; Calcium Chloride (CaCl₂) adds Ca²⁺ and Cl⁻.
Magnesium (Mg²⁺)
Magnesium is a yeast nutrient required in trace amounts. Wort naturally provides adequate magnesium from malt in most cases. At elevated levels (>30 ppm), magnesium tastes harsh, sour, or metallic and acts as a laxative.
Target range: 0–30 ppm. Most brewers aim for 10–20 ppm. Avoid deliberately adding magnesium salts unless your source water is very soft and your malt bill is unusual.
Sources: Epsom salt (MgSO₄) adds Mg²⁺ and SO₄²⁻.
Sodium (Na⁺)
Sodium at low concentrations (50–100 ppm) enhances mouthfeel, rounds out flavors, and accentuates sweetness — useful in malt-forward styles. Above ~150 ppm it becomes unpleasantly salty. Sodium interacts synergistically with chloride to enhance malt character.
Target range: 0–100 ppm for most styles; up to 150 ppm for malt-forward/stout styles.
Sources: Baking Soda (NaHCO₃) adds Na⁺ and raises pH; Table Salt (NaCl) adds Na⁺ and Cl⁻ without significant pH effect.
Chloride (Cl⁻)
Chloride enhances fullness, body, sweetness, and malt character. It complements Sodium's effect. At very high levels (>300 ppm) it can taste mineralic or harsh, and it can stress some yeast strains.
Target range: 50–200 ppm. Higher ranges (150–200+ ppm) suit malt-forward and hazy/New England styles; lower ranges (50–75 ppm) suit dry, hoppy styles.
Sources: Calcium Chloride (CaCl₂), Table Salt (NaCl).
Sulfate (SO₄²⁻)
Sulfate enhances hop bitterness perception, crispness, and dryness. It is the primary tool for pushing a beer toward a drier, more bitter character. At high levels (>400 ppm) it can taste harsh, minerally, or astringent.
Target range: 50–350 ppm. Light lagers and malt-forward styles: 25–75 ppm. West Coast IPA: 200–350 ppm. Burton-on-Trent style bitters: up to 700+ ppm (historically notable but extreme by modern standards).
Sources: Gypsum (CaSO₄), Epsom Salt (MgSO₄).
Bicarbonate / Alkalinity (HCO₃⁻)
Alkalinity (primarily from bicarbonate in most water sources) resists pH drops during mashing. Roasted and crystal malts are naturally acidic and need alkalinity to buffer against excessive acidification. Pale mashes acidify naturally during mashing (primarily via phosphate reactions with calcium), which is the desired effect — they do not need alkalinity support.
Excess alkalinity in pale wort produces harsh, astringent flavors and impairs enzyme activity. It must be balanced with the grain bill.
Target range by wort color:
Very pale (Pilsner)
0–25 ppm
0–30 ppm
Pale (Pale Ale)
0–50 ppm
0–60 ppm
Amber
25–100 ppm
30–120 ppm
Dark (Porter/Stout)
100–250 ppm
122–305 ppm
Sources: Baking Soda (NaHCO₃) raises alkalinity; acids (lactic, phosphoric) reduce alkalinity. Reverse osmosis or dilution with distilled water reduces alkalinity from high-alkalinity tap water.
Residual Alkalinity (RA)
Residual Alkalinity quantifies the net effect of alkalinity and hardness on mash pH. Calcium and magnesium ions precipitate phosphates during mashing, consuming alkalinity. The remaining alkalinity (the "residual" that raises mash pH) is:
RA (as CaCO₃, ppm) = Total Alkalinity − (Ca ppm / 3.5) − (Mg ppm / 7)
Source: Kolbach, 1953
A positive RA means the water will raise mash pH — appropriate for dark grain bills. A negative RA (more calcium/magnesium hardness than alkalinity) means the water will lower mash pH — appropriate for pale grain bills.
RA Targets:
Very pale (Pilsner, light lager)
−50 to 0
Pale ale, Wheat beer
−25 to +50
Amber/Vienna
+50 to +100
Brown Ale, Altbier
+75 to +150
Porter, Stout
+100 to +200
In practice, the primary variable to control is mash pH directly (measure it!) with RA as a planning guide.
Mash pH
Target: 5.2–5.6 (measured at room temperature, ~20 °C)
This is the single most impactful water chemistry parameter. Within this range:
Alpha- and beta-amylase are both active.
Lautering is cleaner (less starch and tannin extraction).
Hop bitterness is smoother.
Yeast performs better in fermentation.
Beer clarity and stability are improved.
pH higher than 5.6 increases risk of harsh, astringent extraction and reduces enzyme performance. pH much lower than 5.2 can reduce fermentability and produce an overly sharp wort profile.
Important: Brewfather predicts pH at 20 °C. When measuring mash pH during the mash (at mash temperatures of 60–70 °C), the measured value will read lower — this is a normal temperature effect, not an equipment fault. Best practice is to cool a sample and compare at room temperature; if measuring hot, expect readings to be roughly ~0.2–0.35 pH lower than room-temperature values.
Factors That Lower Mash pH
Calcium ions (phosphate precipitation from malt)
Acidulated malt
Lactic or phosphoric acid additions
Crystal and roasted malts (to a lesser extent)
Factors That Raise Mash pH
Bicarbonate/alkalinity in source water
Chalk (CaCO₃) — use carefully; see Water Calculator Notes
Baking Soda (NaHCO₃)
Slaked Lime (Ca(OH)₂)
Chloride:Sulfate Balance
The ratio of sulfate to chloride (SO₄:Cl) is a primary dial for steering the overall flavor perception between hop-forward and malt-forward:
< 0.5
Very malty, round, sweet
0.5–1.0
Malt-leaning, balanced
1.0–2.0
Balanced
2.0–4.0
Hop-forward, dry, crisp
> 4.0
Very hoppy, dry (extreme)
Style examples:
NEIPA / Hazy IPA
50–100
100–200
~1:2 (Cl > SO₄)
West Coast IPA
150–300
50–100
~3:1
English Bitter
200–400
50–100
~3:1 to 4:1
Pale Ale (balanced)
100–150
75–125
~1.5:1
Pilsner
10–30
5–25
~1:1 or low overall
Stout / Porter
50–100
75–150
~1:1 to 1:2
Note that the absolute levels of each ion matter alongside their ratio. A beer with 10 ppm SO₄ and 5 ppm Cl has the same ratio as one with 400 ppm and 200 ppm, but very different mineral intensity.
Classic Water Profiles Reference
Famous brewing water profiles have influenced their associated beer styles. These are useful starting points, not rules:
Pilsen
7
2
2
5
6
16
Czech Pilsner; ultra-soft
Dublin
115
4
12
19
53
315
Dry Irish Stout
Burton-on-Trent
295
45
55
25
725
320
English Bitter, IPA
Munich
75
18
2
2
10
152
Bavarian lager
London
70
6
15
38
40
166
English Porter, Mild
All values in ppm (mg/L).
Modern brewers generally build custom profiles targeting specific ion levels rather than blindly replicating historical water. Historical profiles were the result of local geology, not deliberate optimization.
Practical Water Adjustment Decision Framework
Step 1: Know Your Source
Obtain a water report from your municipal supplier or test your well water. Enter it as your Source Water Profile in Brewfather. If your water is variable or you want maximum control, start from Reverse Osmosis (RO) or distilled water (all zeros) and build up.
Step 2: Target Calcium First
Ensure Ca²⁺ ≥ 50 ppm in your mash water. Add Gypsum for SO₄ character or Calcium Chloride for Cl character (or both) to reach target.
Step 3: Set the SO₄:Cl Ratio for the Style
Choose a target ratio based on whether the beer should emphasize hops or malt. Adjust Gypsum vs. Calcium Chloride additions accordingly.
Step 4: Manage Alkalinity for the Grain Bill
Pale grain bill: Aim for near-zero or slightly negative RA. If source water is high-bicarbonate, dilute with RO or acidify sparge water.
Dark grain bill: Allow moderate alkalinity or add Baking Soda in small amounts.
Step 5: Verify Mash pH
Brewfather's Water Calculator predicts pH using the grain type, color, and mineral additions. Verify with a calibrated pH meter during the mash (measure at room temperature or apply correction). Adjust lactic or phosphoric acid additions as needed.
Step 6: Treat Sparge Water
Sparge water should ideally be pH 5.5–6.0. Higher pH during sparging risks extracting tannins from the grain bed as the grain acidification capacity is exhausted. Add a small amount of lactic acid to sparge water if your source alkalinity is high.
Brewfather Tip
Use Brewfather's Water Calculator for every batch, even simple ones. The water calculator does not just help advanced brewers — even entering your source water and checking predicted mash pH can reveal problems before brew day. Here's a practical workflow:
Set your Source Water Profile once in Profiles → Water using your water report or a profile for RO/distilled water.
Open the Water Calculator from the recipe designer (CALC button in the Water section).
Verify grain types — the calculator uses your grain's color category (Base, Crystal, Roasted) to predict pH contribution. Check that Brewfather has assigned each grain the right type.
Check predicted mash pH — target 5.2–5.6 displayed at 20 °C.
Apply AUTO mineral adjustment using a target profile, then fine-tune manually.
Add a small lactic acid addition if your predicted pH is above 5.6 and you want to avoid adding more minerals.
Click "Save adjustments to recipe" — this saves all mineral and acid additions to your recipe's Misc section and produces an accurate brew sheet.
For sparge water pH control, enable sparge acid adjustment in the water settings (⚙️ icon). Brewfather calculates the acid amount needed to reach your target sparge pH automatically.
Acid Additions: Lactic vs. Phosphoric
Both lactic and phosphoric acid are food-safe, non-rinse-required acids used for mash and sparge pH adjustment.
Lactic acid (88%)
80–88% typical homebrew grade
Adds a mild lactic note at very high doses (>0.5 mL/L); barely perceptible at normal rates
Phosphoric acid (75–85%)
Various concentrations
Flavor-neutral; no off-flavor risk; more concentrated
Phosphoric acid (10%)
Diluted solution
Safer to handle; larger volumes needed
For most homebrewing applications, either acid is appropriate. Phosphoric acid is preferred when adding larger volumes or if any lactic character would be off-style. Lactic acid is more widely available and very effective in typical doses (1–5 mL per 20 L batch).
Always enter your acid concentration in Brewfather's Water Calculator settings to ensure accurate dosage calculations.
Troubleshooting Common Water Issues
Harsh, astringent mash or beer
High alkalinity/pH in pale mash
Reduce alkalinity (dilute with RO or acidify); verify mash pH
Thin, sour wort from dark malt
pH too low from highly roasted grains
Increase alkalinity; consider steeping dark malts separately post-mash
Beer tastes salty or harsh
Na or Cl too high
Reduce salt additions; dilute with RO water
Beer feels flat and thin despite good attenuation
Low chloride
Increase CaCl₂ addition
Hop bitterness feels harsh/sharp
Very high sulfate (>400 ppm)
Reduce Gypsum; recalculate SO₄:Cl ratio
Cloudy beer, poor clarity
Low calcium
Ensure Ca²⁺ ≥ 50–75 ppm
Sources
Palmer, John J. How to Brew, 4th ed. Brewers Publications, 2017. (Chapter 15: Water Chemistry; Chapter 16: Adjusting Water)
Palmer, John J., and Colin Kaminski. Water: A Comprehensive Guide for Brewers. Brewers Publications, 2013. (Comprehensive water chemistry reference; RA, ion targets, mash pH)
Kolbach, P. "Berechnung der Restalkalität von Brauwasser." Monatsschrift für Brauwissenschaft 6.6 (1953): 98–99. (Residual Alkalinity formula)
Delange, A.J. "A Brewing Water Chemistry Primer." HomeBrewTalk.com, 2009. (Practical ion guidance, chalk solubility notes)
ASBC Methods of Analysis. "Water and Wort" sections. (Analytical references for alkalinity, hardness, and ion measurement)
Brewfather Docs. "Water Calculator." (20 °C pH convention and workflow references)
Fix, George. Principles of Brewing Science, 2nd ed. Brewers Publications, 1999. (pH and enzyme activity)
Briggs, D.E., et al. Brewing: Science and Practice. Woodhead / CRC Press, 2004. (Alkalinity, sparge water pH, tannin extraction)
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