Chlorine is widely used by drinking water facilities to keep our water safe, but for homebrewers, it can pose a serious problem, affecting flavor and quality in ways you might not expect.
Chlorine in your brewing water
Chlorine plays an essential role in municipal water systems, ensuring our water is safe by killing bacteria and harmful organisms. It’s a key reason why safe water is widely accessible—but it’s detrimental for brewing.
Although chlorine is effective in eliminating harmful microbes, it can produce an unwanted side effect in brewing: chlorophenols. When chlorine interacts with wort, it creates chlorophenols, which add a medicinal, ‘band-aid’ flavor to beer (We aren’t sure why so many brewers know what band-aids taste like, but that’s the most common description)—noticeable to some at even tiny concentrations, as low as 10 parts per billion.
Other sources of Chlorine
Chlorine isn’t only present in water; it can also linger on equipment if you use bleach or chlorine-based cleaners. Residual chlorine can create chlorophenols, so thorough rinsing is essential. Many brewers prefer non-chlorine alternatives, like iodophor or acid-based sanitizers like Star Sans to avoid off-flavors. Many of these brewing specific cleaners don’t require rinsing and lower the risk of residual cleaner getting into the beer.
Free Chlorine vs Total Chlorine vs Chloramines
There are three common ways of measuring Chlorine levels for brewing, free chlorine, total chlorine, and chloramines. But what are the differences?
Free Chlorine is simply the Chlorine that hasn’t interacted with any contaminants and is still “free” to neutralize bacteria. Free Chlorine is the most volatile of any of the compounds and can be removed by exposure to the air, heat, or UV.
Chloramines is another chemical cleaning compound that is a combination of Chlorine and Ammonia. The reason it is used by drinking water facilities is that it is more stable that Chlorine and will sanitize the water for longer. Because it is more stable than Free Chlorine it takes more effort to remove from your brewing water.
Total Chlorine is the sum of all Chlorine in your water, this measures both your Free Chlorine as well as your Chloramines. This will be the most important measurement for your brewing water since any Chlorine can have a negative effect and produce off flavors in your beer.
Chlorine levels for brewing
When brewing, you should always try to reduce your Total Chlorine to 0 to prevent Chlorophenols. This is because Chlorophenols can cause off flavors at as low as 10 ppb.
In your drinking water before treating for Chlorine or Chloramine, it will likely be 0.5 to 2.0 ppm Total Chlorine. From our lab, most of the drinking water we test ends up being close to the 0.5 ppm range.
This range will be easily treated and is acceptable to use for brewing.
How to test for Chlorine in your Brewing Water
When testing for water for Chlorine, the Total Chlorine will be your most important number, this will test for all types of Chlorine including Chloramines. There are two ways to test for Chlorine in your brewing water.
DIY Craft Pro Test Strips will include multiple test strips so you can test multiple batches or test your water at different stages in the brewing process (like before and after treatment for Chlorine).
The other method is to use the Craft Pro In-Lab Test Kit. The In-Lab Craft Pro Test Kit will allow you to send a water sample to our EPA-Certified lab and get exact concentrations of Chlorine in your water sample.
When testing your Chlorine, before you treat for Chlorine your results will likely be anywhere from 1-3ppm. After treatment, your goal will be to have the Total Chlorine test read as 0, meaning it’s negative for any tyle of Chlorine. Since any amount can negatively affect your beer.
How to remove Chlorine from your Brewing Water
Metabisulfite
Metabisulfite, in the form of Sodium Metabisulfite or Potassium Metabisulfite, is the most common way to reduce total Chlorine in your water. These can be Campden Tablets or a powder.
Metabisulfite does not need to be used in the exact amounts, and most brewers purposefully overuse them by a small amount to ensure that Chlorine is completely removed from their water.
These chemicals are not only forgiving in the amount you can use, but also highly affordable. You will need very little, around ¼ of a teaspoon per 5 gallons.
Boiling
Boiling is one of the easiest ways to remove Chlorine and will happen naturally in the brewing process. But it is not as effective at removing Chloramines. Because more water treatment facilities are moving to Chloramines, boiling is not a reliable way of reducing your Total Chlorine to zero.
Air Exposure
Free Chlorine will naturally be reduced when exposed to the air. But like with boiling, this is less effective for Chloramines because they are more stable. It may take one to two days for your water to become dechlorinated with this method and it may not remove all the Chlorine.
This is a method that many homebrewers use and have success with. But it’s not appropriate for commercial brewers who have more invested with larger batches.
Conclusion:
Chlorine in brewing water can significantly impact the flavor of your beer, making it crucial to manage carefully. By understanding the types of chlorine present and using effective testing and treatment methods, you can ensure your brewing water is free of unwanted chlorine compounds. Whether you’re using metabisulfite, alternative sanitizers, or careful testing, a little extra effort can go a long way in preserving the taste and quality of your final brew.
