How to Handle Variable Water Quality

It is difficult to brew with consistency when the quality of your water supply varies. Shifting hardness, alkalinity, and mineral content can make you pull your hair out! Here are some things a brewer can do to help evaluate and correct for a varying water supply. All the following information assumes you have a water report from some point in time for your supply.

The most important factors for brewing water are Hardness and Alkalinity. They are important in establishing the mash pH. Fortunately, there are simple test kits that can be used to establish what your current hardness and alkalinity values are. These kits are widely used in aquarium and water treatment industries. Suppliers such as Hach and Lamotte provide high-quality kits to the water treatment industry and suppliers such as Salifert provide test kits for the aquarium industry that are nearly as precise.

Hardness is contributed by mainly calcium and magnesium in most potable water. Typically, you can obtain hardness test kits that report either Total Hardness, Calcium Hardness, or Magnesium Hardness. If you know that magnesium is typically very low in your water, you may be able to skip testing for Mg. However in most cases, you will need to determine the magnesium and calcium content.

Note that Total Hardness is generally equal to Calcium Hardness plus the Magnesium Hardness. So knowing two of the results will enable you to calculate the other.

With Calcium and Magnesium Hardness values typically reported in “as CaCO3”, grains per gallon, or degrees Hardness values, they need to be converted to true ion concentrations using the calculators on the Water Report Input page of Bru’n Water. Use these new Ca and Mg concentrations as the inputs for your “current” water report.

Alkalinity test kits provide the current condition for your water. Often, those kits report their results in “as CaCO3”, degrees Hardness, or milliequivalents/Liter units. Convert those values to a Bicarbonate (HCO3) ion concentration using the calculators in Bru’n Water for use in the Water Report Input.

With current Ca, Mg, and HCO3 concentrations, you are much more likely to produce the mash pH you target and be able to acidify your sparging water down to a desired low alkalinity. These are the most important things you can do for your brewing.

The final piece of the puzzle is not easily determined: figuring out how the Flavor Ion (Na, SO4, Cl) concentrations have changed as your water source varies. Testing for those ions is not as easy as hardness and alkalinity and testing kits for those ions can be much more expensive. An acceptable work-around is to assess the Total Dissolved Solids of your water using a relatively inexpensive TDS meter. Measuring the current TDS and comparing it with the TDS value calculated in Bru’n Water for the “current” water report that you have created, allows you to proportionally increase or decrease the flavor ion concentrations to bring the calculated TDS closer to the measured value. Although this approach is not highly accurate, it does better account for the current water quality. Please note that the TDS calculation is only available in the Supporter’s version of Bru’n Water.

So, a few inexpensive test kits and a TDS meter can help you bridge your variable water quality and improve the consistency of your beers.

Enjoy!