Boiling water is a common method of purifying water, and it is believed to remove impurities such as chlorine. Chlorine is a chemical compound commonly used as a disinfectant in water treatment facilities to kill bacteria, viruses, and other harmful microorganisms that can cause waterborne diseases. Although chlorine can potentially be harmful to human health if ingested in large amounts, the main issue with chlorine in water is the undesirable taste that comes with it. Therefore, the question of whether boiling water removes chlorine is a common query due to the association between boiling water and a subsequent improvement in water quality.
Boiling will decrease chlorine levels in water, however, boiling can take a long time to completely remove all chlorine from water, due to its diminishing effectiveness as concentrations decline. Despite this, boiling is a great option to reduce chlorine levels in water and improve its taste and smell.
How does chlorine work?
Firstly, it is essential to understand how chlorine works as a disinfectant. Chlorine kills microorganisms by breaking down the cell walls of bacteria and viruses, preventing them from reproducing and causing disease. However, chlorine also reacts with organic compounds in water, such as humic and fulvic acids, to form disinfection byproducts (DBPs). DBPs have been linked to various health problems, including cancer, reproductive and developmental problems, and liver and kidney damage (Richardson et al., 2007).
For a more detailed look at how chlorine works, have a look at my article: What Is Chlorination: A Simple Explanation.
So, Does Boiling Remove Chlorine?
Boiling water has long been believed to remove chlorine from water, and it does, however, research suggests that this is not entirely true. According to a study conducted by the Environmental Protection Agency (EPA), boiling water for 20 minutes can only remove 10% of chlorine (EPA, 2021). This is obviously dependent on the starting concentration of chlorine in the water, A higher starting concentration will result in a larger amount of chlorine being removed in the initial period however, with a lower concentration each subsequent reduction will take longer and longer.
Does Boiling Improve The Taste Of Chlorinated Water?
Chlorine is known to give water a distinct taste and odour that many people find unpleasant. Boiling water can help to reduce the concentration of these species, as they can evaporate along with the water as it boils. As a result, the taste and smell of chlorine in water can be reduced (Wagner et al., 2019).
Research has shown that boiling water can indeed improve the taste of chlorinated water. In a study published in the Journal of the American Water Works Association, researchers analyzed the taste and odour of water samples before and after boiling. They found that boiling water reduced the concentration of chlorine and other volatile organic compounds, resulting in an improvement in taste and odour (Feng et al., 2012).
However, it is important to note that boiling water may not be effective in removing all of the chlorine from the water. While some of the chlorine can evaporate along with the water, not all of it will. Other methods, such as activated carbon filtration or chemical dechlorination, may be more effective at removing these contaminants and improving the taste and odour of water (Environmental Protection Agency, 2021).
Are there downsides to boiling chlorinated water?
There are potential downsides to boiling chlorinated water, boiling water can only remove a percentage of chlorine and can actually increase the concentration of disinfection byproducts (DBPs) in water (Yang et al., 2008). Chlorine is a highly reactive gas that dissolves readily in water to form hypochlorous acid and hypochlorite ions. These species are responsible for the disinfecting properties of chlorine in water. When water is boiled, the temperature causes the water to evaporate and form steam. The steam that is generated leaves behind impurities such as chlorine. However, this process is not very efficient in removing chlorine from water, as it can only remove about 10% of it (Environmental Protection Agency, 2021).
In order to effectively remove chlorine from water, other methods can be more effective including carbon filtration, adding vitamin C, or even simply letting the water sit out. If you are interested in reading more about the other cheap options to remove chlorine from the water I encourage you to have a read of my article: The 4 Easiest Ways To Remove Chlorine From Water
References:
Environmental Protection Agency. (2021). Boiling water. Retrieved from https://www.epa.gov/sites/default/files/2018-09/documents/2005_06_22_faq_fs_homewatertreatment_boil.pdf
Richardson, S. D., Plewa, M. J., Wagner, E. D., Schoeny, R.,
Yang, C., Wang, W., Chen, K., & Lin, Y. (2008). Effects of boiling on the concentrations of trihalomethanes and haloacetic acids in drinking water. Journal of Environmental Science and Health, Part A, 43(2), 139-143. https://doi.org/10.1080/10934520701788402
Wirth, B. W., Wozniak, A. S., & Bajpai, R. K. (2021). Water Treatment. In B. W. Wirth, A. S. Wozniak, & R. K. Bajpai (Eds.), Handbook of Environmental Engineering (pp. 1-25). Springer. https://doi.org/10.1007/978-3-030-48766-8_8-1
Feng, S., Zhang, S., Liu, W., & Cao, H. (2012). Effect of boiling on taste and odour in source water. Journal of the American Water Works Association, 104(8), E456-E463. https://doi.org/10.5942/jawwa.2012.104.0125
