How Water Treatment Affects Mash pH

Why Does Mash pH Matter?

  • Mashing can only be done when the pH is between 5.1-5.3 because that is the desired range for the conversions of sugars. Factors affecting the pH of your mash includes the color and quantity of malt added as well as the ions in the water you are using. Most homebrews have a pH> 5.3 thus there needs to be a type of treatment to bring the pH to about the 5.2 range. 

How to Measure pH:

  • pH (litmus) strips: not as precise
  • precision pH strips: cost effective and practical
  • electronic pH meter: very expensive

How to Change Your Mash pH

  • Add gypsum, epsom salt, or calcium chloride to lower the pH. The calcium and magnesium ions from those chemicals reduce the alkalinity of the water. However you must be very precise when adding these chemicals because the sulfate and chloride react with the phosphorous in the mash, thus producing off-flavors. To determine the correct amount search for specific calculators like this one on Brewer’s Friend.
  • Phosphoric acid, lactic acid, and sulfuric acid will lower the alkalinity of the mash. But again you must be very precise with the amount you decide to use.
  • Lactic Bacteria is added to acid malt for a short period to create a reaction that yields lactic acid. This will lower the pH.
  • Acid rest breaks down phytins in the malt to yield phytic acid, which then lowers the pH
  • Add 5.2 Stabilizer (a powdered additive) to lower your pH to exactly 5.2

Why Does Water Treatment Matter:

  • Because beer is 95% water, the type of water you use in homebrewing will contribute to the taste of your beer.  Chlorine and chloramine in water will react with the malt phenols in the wort to yield chlorophenol- a compound that gives beer a medicinal taste. The chlorine can also kill or reduce the metabolism of your yeast. Different styles of beers require different water profiles. 

What Each Ion Does:

  • Chloride will affect the mouthfeel and complexity of beer. Accentuates malt character. Too much chloride will give a medicine-like flavor.
  • Chlorine reacts with aromatic compounds called phenols in the malt, which will yield chlorophenols that give an off-flavor. 
  • Bicarbonate & Carbonate determines the acidity of the mash (if levels are low then the pH is low and vice versa). It neutralizes the acidity of dark roasted malts. Reduces water hardness by binding with calcium when boiled.
  • Sodium affects the mouthfeel and body of your beer. Too much will result in a seawater taste
  • Sulfate brings out hop bitterness and dry sharp hoppy feeling. It lowers the pH. Too much sulfate brings an astringent flavor to your beer.
  • Calcium lowers the pH while mashing and helps precipitate proteins during the boil. It also acts as a yeast nutrient and helps with beer stability.
  • Magnesium reduces mash pH. It also acts as a yeast nutrient and affects water hardness. Too much will give a sour, dry, harsh taste to beer.
  • Potassium blocks enzymatic reactions in the mash.

How to Treat Each Ion:

  • Chlorine:  Use a Campden tablet (1 tablet will work for 20 gallons) or purchase a carbon block water filter that attaches to the faucet.
  • Bicarbonate & Carbonate: You want 25-50mg/l for pale beers and 100-300mg/l for darker beers
  • Sodium: Add table salt (sodium chloride) to accentuate bitterness and enhance flavors and fullness of beers. Sodium chloride accentuates caramel flavors in malty beers. Want between 10-70mg/l, up to 150mg/l can enhance malty body and fullness while any level above 200mg/l is undesirable.
  • Chloride: Want less than 150mg/l and never to exceed 200 mg/l.
  • Sulfate: For pilsners and light ales you want 10-50mg/l. For most ales you want 30-70mg/l.
  • Calcium: Add calcium chloride to increase levels. Want level to be between 50-150mg/l.
  • Magnesium: Use Epsom salt to increase magnesium sulfate levels. Want 10-30mg/l. Be careful in doses because magnesium sulfate is a diuretic and thus can lead to dehydration.

The following table is from John Palmer How To Brew Table 16 – Salts for Water Adjustment

Brewing Saltand Common Name Concentration at 1 gram/gallon Grams per level teaspoon Effects Comments
Calcium Carbonate (CaCO3) a.k.a. Chalk 105 ppm Ca+2 158 ppm CO3-2 1.8 Raises pH Because of its limited solubility it is only effective when added directly to the mash. Use for making dark beers in areas of soft water. Use nomograph and monitor the mash pH with pH test papers to determine how much to add.
Calcium Sulfate (CaSO4*2 H2O) a.k.a. Gypsum 61.5 ppm Ca+2 147.4 ppm SO4-2 4.0 Lowers pH Useful for adding calcium if the water is low in sulfate. Can be used to add sulfate “crispness” to the hop bitterness.
Calcium Chloride (CaCl2*2H2O) 72 ppm Ca+2 127 ppm Cl-1 3.4 Lowers pH Useful for adding Calcium if the water is low in chlorides.
Magnesium Sulfate (MgSO4*7H2O) a.k.a. Epsom Salt 26 ppm Mg+2 103 ppm SO4-2 4.5 Lowers pH by a small amount. Can be used to add sulfate “crispness” to the hop bitterness.
Sodium Bicarbonate (NaHCO3) a.k.a. Baking Soda 75 ppm Na+1 191 ppm HCO3 4.4 Raises pH by adding alkalinity. If your pH is too low and/or has low residual alkalinity, then you can add alkalinity. See procedure for calcium carbonate.

John Palmer also suggest that there should be a balance between sulfate and chloride:

  • 2:1 SO4 to Cl is good for bitter beer
  • 1:2 SO4 to Cl for mild ales
  • 1:3 SO4 to Cl for stouts and porters
  • Chloride and Sodium add the maltiness of a beer.
  • Sulfate highlights bitterness and reduces malt flavor.



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