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Does Chlorine Evaporate from Tap Water?

Scott Winfield
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by Scott Winfield

For many decades, chlorine has been the silver bullet for disinfecting water. Like most chemical additives, there’s the issue of remnants after water disinfection.

So, does chlorine evaporate from tap water? Yes, because chlorine is slightly volatile it will evaporate slowly from the water’s surface if left still for a while.

Tap Water

How Long Does It Take Chlorine To Evaporate From Water?

It takes approximately 24 hours for chlorine to evaporate from water. However, there are instances when chlorine might take much longer to evaporate. If the total volume of water and chlorine concentration is high, it will take up to five days to evaporate.

Some conditions can speed up the evaporation process. They include aeration, ultraviolet light, and proper circulation.

While dechlorinating water through evaporation is time-consuming, it is the safest method. Removing chlorine from a large volume of water can be expensive, especially when using other methods.

With evaporation, you only need to be patient to have chlorine-free water. It typically takes 110 hours (four and a half days) to evaporate chlorine at a level of 2 ppm in 10 gallons of water.

The Best Ways To Remove Chlorine

Evaporation is one of the best methods to eliminate chlorine from water. Evaporation is easy, but it will take longer than other processes.

The chlorine in your tap water evaporates in about 1-2 days. After two days, you can be rest assured of the absence of chlorine. Test your water correctly to ensure no chlorine is left behind. Also look out for common signs of chlorine smell in the house.

Chlorine decontaminates water, but high chlorine concentration causes long-term health issues.

According to the CDC, chlorine concentrations of up to 4 mg/L are safe in drinking water. If these levels exceed 4 mg/L, consider seeking ways of reducing chlorine in your tap water.

What if you’re in a hurry and wish to remove chlorine from your water faster? Whether you’re dechlorinating water for consumption or commercial purposes, you can use other effective methods.

Now that you have the answer to the question, does chlorine evaporate from tap water, it’s time to learn the best ways to remove chlorine from water.



Boiling water is one of the best ways to make it safe for drinking. Although boiling is known for inactivating germs/pathogens, it’s also an effective way of removing chlorine from water.

Boiling removes harmful disinfectants, including chloramine, in a few minutes. Unlike chlorine, chloramine is stubborn when removing it from water through evaporation. It takes longer to remove chloramine because it’s less volatile than chlorine.

If you don’t want to wait long, boiling your water can come in handy. There should be sufficient heat and aeration to eliminate chlorine and chloramine when boiling water. To get the best results, boil water consistently for about 20 minutes.

It takes about eight minutes to eliminate 1 ppm of chlorine in 10 gallons of water. When you put water to consistent heating, you reduce its ability to hold dissolved gasses. When you boil your chlorinated water, the chlorine will evaporate in a few minutes.

Boiling smaller quantities of water is fast and more sustainable. It might take you longer if you’re boiling water for commercial use. Large volumes of water in industries will take 10-15 minutes to boil and remove chlorine.



Filtration is the most effective and the fastest way of removing chlorine from water. This method also ensures no contaminants are left behind. Most water filtration systems use a process known as reverse osmosis. Water passes through a permeable membrane that removes ions, particles, and impurities.

Filtration is a less laborious method. It functions automatically, to remove chlorine and other contaminants.

Keep in mind that some filtration options are costly and installations can be daunting.

Adding Ascorbic Acid

Adding Ascorbic Acid
Adding Ascorbic Acid

Adding ascorbic acid to water can get rid of chlorine in a few minutes. Ascorbic acid neutralizes and precipitates chlorine. A standard measure of ascorbic acid is required to remove chlorine in the water.

For example, if you want to get rid of chlorine from one gallon of water, you should add one tablespoon of ascorbic acid. Ascorbic acid (vitamin C) does not dissolve in water. Once you have the right amount, sprinkle it on the water surface and stir gently.

If you wish to get rid of chloramine from tap water, ascorbic acid can help. However, you need to use a large amount of vitamin C. The good news is that ascorbic acid is cheap, and you can find it in most pet stores.

Sodium Metabisulfite

Sodium Metabisulfite
Sodium Metabisulfite

Like ascorbic acid, sodium/potassium metabisulfite is effective in dechlorinating water. The chemical comes in the form of small tablets. The number of tablets to use depends on the amount of water in your tank. You should put one tablet in 20 gallons of water and wait for it to dissolve.

The tablet will neutralize the chlorine and chloramine before evaporating. This method works quickly, and most breweries and wineries use it. When used at home, potassium metabisulfite will get rid of chlorine in a few minutes.

Ultraviolet Light

Ultraviolet Light
Ultraviolet Light

Removing chlorine from water through ultraviolet light is expensive and can take longer. First, you need to install a bulb that will act as a UV light source.

The bulb is costly, and you have to change it more often. Once you’ve installed the bulb, you should ensure the UV rays go directly to the tank. The UV rays will remove all chlorine in your water in minutes.

If the UV light is not enough for the water in your tank, this method won’t be effective. When using ultraviolet light, measure the amount of water in square centimeters or gallons.

You will need a UV light wavelength of about 254 nanometers for every square cm of water. You’ll also require a radiant energy density of 600 milliliters.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
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