The Big Six Water Ions and Water Chemistry in Beer Brewing

The Big Six Water Ions

When we measure our starting brewing water or adjust our water, there are six main ions dissolved in the water that drive the mash pH as well as the brewing chemistry. Understanding these ions is critical for achieving the results you want as well as how to adjust your water to fit a particular style or type of beer.

If you are looking to measure the water you regularly use for brewing, these are also the ions you want to measure. There are several ways to find out the ion content of your water, including local water reports, brewing test kits or by sending a sample off to a lab.

These water ions are typically listed in parts per million (ppm) though you may also see them as mg/L which is the same thing. Here are the six along with the recommended ranges to use for brewing.

Copper beer brewing equipment

• Calcium (Ca) [50-100 ppm] – Acidifies the mash and drives down the mash pH which is generally a good thing in lighter color beers. It also aids in precipitating phosphates and improving the stability of the beer. Calcium also provides some structure to the beer and is used in that role as well.

• Bicarbonate (HCO3) [0-250 ppm] or Alkalinity [0-200 ppm] – Strongly alkaline so it will raise the mash pH which is undesirable in lighter color beers. High levels also will impede the cold break and emphasize bitterness in a harsh way. The main role for these ions is in mash pH balance, and too much alkalinity can be undesirable. You can convert from bicarbonate to alkalinity using this equation: alkalinity = bicarbonate * 50 / 61.

• Sulfate (SO4) [50-250 ppm] – Suilfate enhances bitterness in beer and slightly lightens color. Its primarily role is as a counterbalance to chloride in determining the sulfate/chloride ratio which affects bitterness perception in the final beer.

• Chloride (Cl) [0-250 ppm] – Chloride will lower the bitterness perception and enhance the maltiness of the beer. Its major role, along with sulfate, is in determining the sulfate/chloride ratio which affects bitterness perception in the beer.

• Sodium (Na) [0-150 ppm] – Sodium provides enhances the sweetness and body in certain dark beers. However it is not a major player in mash pH so it is primarily used to provide some roundness in darker beers.

• Magnesium (Mg) [10-40 ppm] – Magnesium plays an important role in fermentation as it is needed by yeast, but grains in the mash do provide about 100ppm of magnesium. However, recent research indicates that calcium may actually block the yeast’s access to magnesium if it is very high. So it may be important to keep the total magnesium levels (water plus magnesium from the mash) above the calcium to enhance yeast health. Magnesium also plays a small role in mash pH, but is largely overshadowed by bicarbonate and sulfate.

Hop pellets

When looking at the big six ions, I prefer to pair the first four. Calcium and bicarbonate primarily affect mash pH and they work in opposite directions, so I focus on these when looking at where my mash pH should fall and how I might need to adjust it. Similarly I pair together sulfate and chloride and look at the sulfate/chlrodie ratio to determine the malt-hop perception in the finished beer. Sodium, which provides structure, is something I adjust mainly for darker beers. Magnesium is important for fermentation, so I make sure I have at least a small amount available for yeast, though as mentioned above you also want to consider calcium levels and add more magnesium if you are working with a high calcium profile.

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