Potassium— found naturally in malt—is a key ion in wort and has subtle effects on both enzyme activity and flavor perception. While it’s present in nearly all brewing malts, understanding its thresholds and interactions helps you manage mash performance and final beer character.
How does Potassium affect your beer?
Potassium is required for yeast growth and supports fermentation. It is largely going to be found in the malt and has minimal impact on the flavor of beer.
At higher levels, it may add a saltiness to the beer. It is commonly used in winemaking because of how it interacts with compounds in wine, but in beer brewing these compounds are not present so there is no need to add extra potassium.
Potassium amount in brewing water
Potassium typically does not need to be added to brewing water because it comes from the malt. In most tap water it will be found in very low concentrations, typically around 2 ppm.
Potassium in water above 10 ppm can harm your fermentation.
Malt will typically add 300 to 500 ppm to the wort. This range is almost common for potassium concentrations in beer.
Testing your Water’s Potassium Levels
To determine the potassium concentration in your water, you should use the CraftPro Master Brewer’s Test Kit.
The CraftPro In-Lab test kit will let you send in a sample to our laboratory to have it tested for potassium and 14 other parameters that are critical to brewing such as magnesium, chloride, and sulfate. As well as two brewing specific calculations that affect your water profile.
The CraftPro Master Brewer’s Test Kit makes it easy to get your results. After you order your test kit you’ll get everything you need to collect a sample and send it to our lab. Once we analyze your sample, we’ll send you an easy-to-read, electronic report with exact concentrations and calculations done for your sample.
How to reduce potassium concentrations in brewing water
Reverse Osmosis Filtration has become extremely popular in the brewing community. This is because it will take your water profile to a blank slate. This is an effective way to remove everything you do not want in your water, but it will also remove everything beneficial.
If you are using a reverse osmosis filtration system, you will need to build your own water profile by adding the minerals back in. If you do not know where to start, you can look at our brewing profiles page to see what many popular brewing cities have as their default water.
When to add potassium to brewing water
Many brewers will use potassium metabisulfite to cancel out disinfectant in their water. While sodium metabisulfite does the same task. Potassium has less flavor impact that sodium does.
Potassium is often combined with other compounds to add to brewing water because it has minimal impact on flavor and fermentation and low concentrations.
