Calcium Hydroxide (Slaked Lime) is a powerful brewing water treatment used to increase residual alkalinity and raise mash pH in brewing water. Also known as Pickling Lime or Slaked Lime, it is commonly used by brewers seeking precise control over their water chemistry when brewing darker beer styles or modifying water profiles.

Water chemistry has a significant impact on mash performance, fermentation, flavour development, and overall beer quality. Calcium Hydroxide (Slaked Lime) provides a highly effective method of increasing alkalinity, helping brewers offset the acidity of darker malts and achieve optimal mash pH levels.

Unlike some other alkalinity-raising brewing salts, slaked lime is extremely potent and should be used carefully. Accurate calculations and gradual additions are essential to avoid over-correcting water chemistry and creating excessively alkaline brewing liquor. For this reason, many brewers use brewing water software such as BrewFather to accurately determine the required dosage based on their source water and target profile.

In addition to increasing alkalinity, Calcium Hydroxide (Slaked Lime) contributes calcium to brewing water. Calcium is one of the most important brewing minerals, supporting mash enzyme activity, protein precipitation during the boil, yeast health, beer stability, and clarity.

Because of its effectiveness and strength, Calcium Hydroxide (Slaked Lime) is most commonly used by brewers with a solid understanding of water chemistry who are looking to build precise brewing water profiles for specific beer styles.

Whether you’re adjusting soft water, raising mash pH, or fine-tuning a custom water profile, Calcium Hydroxide (Slaked Lime) is a valuable tool for advanced brewing water management.

Key Features

• Raises residual alkalinity
• Increases mash pH
• Contributes calcium to brewing water
• Suitable for advanced water profile adjustments
• Ideal for brewing darker beer styles
• Supports custom water chemistry management
• Highly effective alkalinity adjustment agent
• Compatible with brewing water calculators and software
• Commonly used with BrewFather water profiles
• Suitable for all-grain brewing

Benefits for Brewers

Raises Mash pH

• Helps offset acidic malts
• Improves mash balance
• Supports optimal brewing conditions

Increases Residual Alkalinity

• Useful for darker beer recipes
• Assists water profile adjustments
• Supports custom brewing water targets

Adds Calcium

• Supports enzyme activity during mashing
• Improves yeast performance
• Enhances beer clarity and stability

Ideal Beer Styles

• Stout
• Imperial Stout
• Porter
• Brown Ale
• Dark Mild
• Schwarzbier
• Baltic Porter
• Other dark malt-forward beers

Water Chemistry Information

Calcium (Ca)

Calcium is one of the most important brewing minerals and contributes to:

• Improved mash efficiency
• Better protein precipitation during the boil
• Enhanced yeast health
• Increased beer stability
• Improved beer clarity

Recommended brewing range:

• 50–150mg/L

Many brewers aim for approximately 100mg/L calcium for optimal brewing performance.

Using Calcium Hydroxide

When using Calcium Hydroxide (Slaked Lime):

• Add carefully and gradually
• Monitor pH throughout adjustments
• Avoid over-correction
• Use a brewing water calculator where possible
• Follow recommended water chemistry guidelines

Because slaked lime is highly effective, only small additions are often required to achieve significant changes in alkalinity.

Water Profile Adjustment

Brewers commonly use water treatment salts to achieve specific brewing water profiles.

Common brewing salts include:

• Calcium Hydroxide (Slaked Lime)
• Calcium Carbonate (Chalk)
• Calcium Sulphate (Gypsum)
• Calcium Chloride
• Magnesium Sulphate (Epsom Salt)
• Baking Soda

For best results, use brewing software such as BrewFather to calculate accurate addition rates based on your source water analysis and target beer style.

Product Information

Product Type:
Brewing Water Treatment

Also Known As:
Slaked Lime, Pickling Lime

Primary Ion Added:
Calcium (Ca)

Primary Function:
Increase Residual Alkalinity and Raise Mash pH

Suitable For:
Water Chemistry Adjustment, Mash pH Control, Dark Beer Styles, All-Grain Brewing