Brewing Water Primer
Introduction To The Topic Of Brewing Water
By Colin Kaminski
Water makes up most of a beer. While it has long been known that water effects the flavor of beer dramatically many brewers have left this important ingredient out of their studies about beer and recipes. Water needs to be free of impurities that can cause flavor problems and/or process problems.
By far the most common water problem affecting brewers is chlorine/chloramine. Chlorine makes a plastic/Band Aid/Phenolic flavor in beer. Chlorine is put into water by municipalities to disinfect their distribution systems. It is very short lived and very effective. The problem comes from dead legs, places in the water distribution with low or no water flow. In dead legs the chlorine can be depleted and the water can grow organisms. Some potential organisms can be pathogenic, others simply add off flavors or aromas to tap water. The solution to this problem is replacing chlorine with chloramine. Chloramine is much longer lived and will sanitize dead legs easily. It is this long lasting nature that makes it more difficult to remove.
To remove chlorine heating the water to strike temperature is often all that is needed. You can do a total chlorine test to see if that is sufficient for you are you can cool a sample and taste it. However, even boiling will only slowly remove chloramine.
To remove chloramine you either have to slowly pass it through carbon filters or add a campden tablet (sodium metabisulfite or potassium metabisulfite) to the water and heating. The dosage is about 1/4 tablet per 5 gallons of water.
It should be noted here that once the sanitizer is removed from the water it will tend to grow things again and keeping your water system clean after the charcoal filter is important. Large breweries are designed to be able to clean after the charcoal filters with steam.
Iron is another common contaminate of brewing water. While it is possible to chemically remove iron it is much easier to install a filter rated for iron removal if you have an iron problem in your water. The presence of iron can be easily tested or you can simply look at your bathtub and sink for red stains where the faucets drips. Iron makes a metallic blood like taste in beer.
Different water supplies might have other contaminations of interest. A particularly problematic one is when a surface water has organic matter that gets picked up and chlorinated. This produces a swamp water taste in beer and is detectable at very low thresholds (ppb). It can be removed by carbon filtration.
Once we are sure we are not creating any off flavors or process problems with our water we need to concern ourselves with setting the mash pH. Proper mash pH is very important to getting the proper malt and hop flavors from brewing. Mash pH is measured on a chilled (68F) sample a few minutes after hydration. Interestingly you can mix the grain and water cold and measure the mash pH for testing. Heating the mash does not change the pH. This is useful for trials of base malts. In natural water calcium and magnesium act to lower the mash pH and alkalinity acts to raise it. Most base malts want to mash in at about 6 pH with distilled water. A much better pH is 5.2 to 5.4. While this lowers efficiency slightly it is accepted that the malt and hop flavors are improved.
In order lower the mash pH calcium chloride, calcium sulfate (gypsum) and magnesium sulfate (Epsom) can be used. Dark malts will also lower mash pH and usually darker beers require some alkalinity to raise the mash pH. Baking soda is very easily dissolvable and is quite effective at raising the mash pH. Having a pH meter is very handy but pH paper can be useful as well.
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