Does Boiling Water Remove Chlorine (and Chloramine)?


Natural Chlorine removal methods eventually become of interest to anyone who keeps aquarium fish or just dislikes the taste of chlorinated water.

You could remove Chlorine from tap water by boiling it, but will that be enough to completely drive it out?

What about its less volatile and more stable substitute – Chloramine?

Will such a treatment yield sufficient results?

Does boiling tap water remove Chlorine efficiently?

Here’s what happens with water when being boiled and if that removes free Chlorine:

Boiling tap water is efficient in removing free Chlorine from it because there’s an inverse relationship between a liquid’s temperature and how much dissolved gas it can hold. Free Chlorine remains as dissolved gas in water at temperatures of above -29.2 °F or -34 °C. Therefore boiling chlorinated water will decrease its ability to hold gasses and force the free Chlorine to leave it.

Boiling city water can be a quick and natural way to rid it from Chlorine and make it safe for aquarium fish or simply eliminate the unpleasant taste for drinking purposes.

What about boiling out Chloramine?

Chloramine is the chemical bond between Ammonia and Chlorine and is less volatile and reactive than the free Chlorine molecules.

These qualities enable Chloramine to stay a lot longer in water than Chlorine and are the main reason why most water facilities switch to it for disinfection.

Here’s if boiling helps with Chloramine removal from tap water:

Boiling speeds up the evaporation of Chloramine from tap water significantly, but it still remains a relatively slow process. You’ll need to boil 10 gallons of water for at least an hour to completely remove 1 mg/L (milligram per Liter) of Chloramine. Therefore it’s not feasible to try and boil Chloramine out of larger volumes of tap water.

Rarely, your city water will contain less than 2 mg/L of Chloramine, and in some cases it can contain up to 4 mg/L as per the Environmental Protection Agency’s regulation.

How long should you boil the water for the complete evaporation of Chlorine and Chloramine?

Chloramine takes up to 17 times longer than Chlorine to leave boiling water.

However, Chlorine outgasses relatively fast under the same conditions.

I did some research and made my own measurements, which gave me these results.

Visit the link where I discuss evaporation speeds of Chlorine and Chloramine in detail, and also provide a chart which can be used to calculate the needed time to boil your tap water.

A concentration of 1 mg/L of Chlorine will take 3.7 minutes to evaporate from 10 gallons of boiling water. The same amount of Chloramine will take a little over 60 minutes.

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