Ask Mr. Wizard

The Salty Truth About Softeners


Scott A. Howard • Winona, Minnesota asks,

I have been brewing for more than seven years now, mostly using extracts and specialty grains, with excellent results. I use city water, which runs through a water softener and charcoal filter to remove the chlorine. You’re probably thinking, “Softened water and all those sodium ions — your beer probably tastes like the ocean!” Actually, I use potassium chloride in our water softener instead of sodium chloride. The potassium chloride is readily available in our area as a substitute for more traditional softener salt and is advertised as a healthier alternative to humans and plant life. Are the potassium ions present in my brewing water a desirable addition?


Potassium chloride is commonly sold as an alternative to sodium chloride. Those companies that market potassium chloride make the point that it doesn’t do all the terrible things to the body that sodium does and that potassium is necessary for the body to properly function. Potassium is indeed required by the body, but sodium is also required. Both are integral parts of the sodium-potassium pump that maintains a membrane across the cells of the body. Anyhow, most diets supply ample potassium and sodium, and few Americans need to supplement their diets with either of these elements.

The heart of the matter lies in what effect, if any, potassium has on beer. Yeast cells do not require any dietary supplements of potassium, and the potassium does not affect mash pH like calcium, magnesium, and carbonate do. However, potassium chloride does have a salty flavor similar to the taste of sodium chloride and also has some metallic flavor notes. These flavors will find their way to your finished beer if your softened water has a high concentration of potassium.

In general I do not suggest using water from salt-based softeners for brewing — or drinking for that matter — because the water usually tastes funky. The primary use for these water softeners is to remove calcium and magnesium hardness that react with carbonates to form scale in pipes, water heaters, and dishwashers. Soft water also works better for doing laundry and lathering up the body in the shower. None of these things has anything to do with brewing an excellent beer or producing a pleasant-tasting glass of water. In fact certain key minerals, especially calcium, that are very important to mashing, trub formation in the boil, and yeast performance are the same minerals removed by salt-based water softeners.

Many of the most prized brewing centers in the world have very hard ground water. Burton-on-Trent, Dublin, London, Edinburgh, and Munich all are hard-water towns. Certain types of beers such as pale ale, stout, dark lager, and other similar styles turn out quite well with hard water. Light beers such as pilsners usually turn out best with soft water and the brewers of Munich do not use its famed “dark lager water” for brewing their light lagers.

The point is your city water may be great brewing water without any treatment except for the removal of chlorine with a charcoal filter or heat. I would get my hands on a water analysis and a good article on brewing water to help decipher the analysis. If you still want softer water after reading the analysis, consider some other techniques such as boiling or buying bottled drinking water. Softened bottled water is treated with other techniques that leave very little in the water but water! Bottled water usually works best for brewing if you add some calcium sulfate (gypsum) or calcium chloride.


Response by Ashton Lewis.