Chlorine and Chloramine = Flavor & Aroma Killers

When we make homebrew, we usually think about ingredients like malt, hops, honey, or fruit. But there is another ingredient that is just as important: water.  Most homebrewers use tap water, and that water often contains chemicals called chlorine and chloramine. These chemicals are added by cities to keep drinking water safe, but they can cause problems in fermentation if we don’t deal with them first.  Understanding what they are and how to remove them is a simple skill that can make a big difference in the quality of your homebrew.

What Are Chlorine and Chloramine?

Chlorine and chloramine are chemicals used to disinfect drinking water.  Their job is to kill harmful microorganisms like bacteria and viruses so that the water coming out of your tap is safe to drink.  Chlorine is a strong disinfectant that has been used in water treatment for more than a hundred years.  Chloramine is a more stable disinfectant made by combining chlorine with ammonia.  Both chemicals do the same job: they keep the water supply safe while it travels through miles of pipes to your home.

Why Cities Use Them

Water treatment plants add chlorine or chloramine because water systems are large and complex.  After water leaves the treatment plant, it travels through many pipes before reaching homes and businesses. During that time, bacteria could grow if the water were not protected.  Chlorine and chloramine stay in the water at very small concentrations and continue working as disinfectants, helping keep the water safe until it reaches your tap.  From a public health perspective, these chemicals are extremely important. They have helped prevent many waterborne diseases.

Why We Don’t Want Them in Homebrew

Even though chlorine and chloramine are safe for drinking water, they can cause problems in fermentation.  When these chemicals react with compounds in malt, hops, or other ingredients, they can create compounds called chlorophenols.  Chlorophenols produce flavors and aromas that most brewers consider unpleasant. People often describe them as plastic-like, medicinal, or bandage-like.  These flavors can appear even when only tiny amounts of chlorine or chloramine are present.  Because fermentation is sensitive to water chemistry, many brewers make it a habit to remove chlorine and chloramine before brewing.

How to Remove Chlorine and Chloramine

Chlorine is relatively easy to remove from water.  One simple method is letting the water sit uncovered for several hours. Chlorine is volatile, which means it slowly evaporates into the air.  You can also remove chlorine by boiling the water, running the water through a carbon filter, adding a small amount of Campden tablet (potassium or sodium metabisulfite).  For many homebrewers, a simple carbon filter or Campden tablet is the easiest solution.

Chloramine is more stable than chlorine, which means it does not evaporate easily.  Letting water sit overnight usually will not remove chloramine.  The most reliable ways to remove chloramine are Campden tablets or activated carbon filtration.

Campden tablets are very popular among homebrewers because they are simple to use. A small amount added to brewing water quickly neutralizes both chlorine and chloramine.

A Small Step That Makes a Big Difference

Chlorine and chloramine are intended to be undetectable by the time it reaches our homes.  You may or may not taste or smell them in plain tap water, but they can affect the flavor of a finished beer, mead, or cider.  Fortunately, removing them is one of the easiest improvements a brewer can make.  A simple water treatment step can help protect the flavor of your fermentation and prevent off-flavors before they start.

The NTHBS team is happy to help you with your homebrew water questions!

Here’s a link for more info on our metabisulfite products at NTHBS!

Cheers!

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