Will Chlorine Evaporate From Tap Water

Writing is a hobby of mine – a side hustle. But, I’m also a water operator at a plant that can treat up to five million gallons a day. I have been concerned about drinking tap water since my mid-twenties, way before I was a licensed water operator. 

I remember reading the consumer confidence report from my city that broke down all of the nasties in my tap. Trace amounts of arsenic, fluoride, and chlorine were mentioned. The report said the concentration of contaminants was too low to be harmful. But, I still wanted to know how to remove all of it. Unfortunately, I couldn’t afford a good water filter. So, I Googled other ways to remove the items.

One of the chlorine removal methods I stumbled across was evaporation, so I started leaving a pitcher of water on the countertop for twenty-four hours before I drank it. I had no way to test the method, so I just hoped and assumed it was working. 

Now that I work at a water plant, I do have a way to test for chlorine removal via evaporation, so I decided to do it!

Will Chlorine Evaporate from tap water?

Why Chlorine is Used for Purification of Water

Before I became a water operator, I was suspicious of the use of chlorine in drinking water. 

“Why should people have to buy home filters to remove chlorine and other contaminants? Why can’t the water treatment plant clean water the way home filters do?” I wondered.

When I got licensed, I learned why chlorine and chloramines are used.

According to the Center for Disease Control, “Water comes from a variety of sources, such as lakes and wells, which can be contaminated with germs that may make people sick. Germs can also contaminate water as it travels through miles of piping to get to a community. To prevent contamination with germs, water companies add a disinfectant—usually either chlorine or chloramine—that kills disease-causing germs such as SalmonellaCampylobacter, and norovirus.”

In other words, drinking water directly from the lake will make you sick. But, the key to understanding why chlorine and chloramines are used is found in distribution. Notice how the CDC says, “Germs can also contaminate water as it travels through miles of piping”? That’s why water in distribution is required to have a chlorine residual.

Is it Safe to Drink Chlorinated Tap Water?

The official stance of the CDC and the EPA is that chlorinated tap water is safe to drink in small amounts which is no more than four milligrams of chlorine per liter of water. 

That’s the official stance.

But the CDC also tells us not to use tap water in fish tanks because it kills aquatic life. I don’t want to drink water that kills aquatic life, whether it’s deemed “safe” or not. 

According to the National Library of Medicine, “Several epidemiological studies indicated a possible association between drinking chlorinated water and increased risk of cancer.”

That doesn’t mean I think there is anything malicious about conventional water treatment. I just think it’s the lesser of two evils. People can’t just drink lake water because of harmful parasites, viruses, and bacteria. I understand that chlorination is the best way to treat water for large municipalities, but that doesn’t mean it’s a perfect solution. It’s just the best solution on a wide scale.

The government is doing its part to protect the public from unsafe drinking water, but you are ultimately responsible for your own health. That’s why it’s important to investigate further and see if there are other steps that you can take to ensure you are drinking the safest water possible!

Will Chlorine Evaporate From Tap Water? An Experiment

Hypothesis

I was trained to test collected water samples as soon as possible to achieve an accurate reading because chlorine evaporates so quickly. But, I wanted to experiment to see how long it would take for a significant amount of chlorine to evaporate from water. 

The results were shocking!

Materials

  • Hach SL 1000 Portable Parallel Analyzer
  • Chem Keys – Total Chlorine, Monochloramine, and Free Ammonia
  • Glass Beaker – 1000 mL capacity

Process

  1. I rinsed the glass beaker thoroughly with water from the D4 sample line (distribution water) and filled the beaker. I had to fill it farther than the 1000 mL line so the chem keys would reach the sample!
  2. I dipped the chem keys into the sample as soon as I filled the beaker and recorded those results.
  3. I stored the water in an undisturbed location at room temperature for about 4 hours, to allow the chlorine to evaporate.
  4. After about 5 hours I tested the sample of water again and recorded the results.
  5. After about 24 hours I tested the sample of water again and recorded the results.

Results

Will Chlorine Evaporate From Water
This is the first sample of D4 water. You can see the amount of total chlorine present is 3.87mg/L
Will Chlorine Evaporate From Water
This is the second reading that I took about 5 hours later. You can see the amount of chlorine dropped to 3.69 mg/L.
Test Results
This is the final reading I took after the water sat for about 24 hours. The chlorine content was reduced to 3.14 mg/L through evaporation.

Conclusion

The amount of chlorine was reduced after having time to evaporate, but not by a significant amount. This is likely because my water plant uses monochloramine because it lasts longer in distribution than chlorine. In other words, monochloramine is resistant to evaporation. 

Many water plants use monochloramine vs. chlorine for this reason. Remember, having a chlorine residual in distribution is important to prevent water borne diseases, which is good. But, that doesn’t mean chlorinated water is the healthiest water to drink!

How to Remove Chlorine From Tap Water

Please Don't Buy Bottled Water!

Please don’t buy bottled water. It’s stored in plastic, which is carried in non-temperature-controlled trucks, which means chemicals from the plastics could leech into the water. Also, that’s just way too much plastic. And think about the fossil fuels required to transport all of those tiny bottles! 

Plus, an experiment I conducted revealed trace amounts of chlorine in a popular water brand. Read about it, here.

Don't Boil Tap Water!

Some say you can boil tap water to remove chlorine levels, but I wouldn’t recommend it if fluoride is added to your tap water, because boiling water can increase fluoride levels. In addition, boiling won’t remove heavy metals like arsenic. Remember how I said my community water report revealed arsenic was in the tap?

Find a Water Station Near You

I live in the country and have the luxury of drinking pure water from my private well. But, back when I lived in the city, after I got tired of trying to evaporate chlorine one pitcher at a time, I used water stations. 

Purchase a BPA-free five-gallon jug and take advantage of a water refill station near you. They can be found outside of grocery stores and in parking lots of shopping plazas. Water stations are serviced regularly, and offer numerous on-site filters that significantly reduce chlorine and other contaminants.

The only downside to a water refill station is that you are putting your trust in the technician who services the filters. If someone gets lazy, they may not change the filters as often as they should.

Invest in a Home Filter

The best way to protect yourself from drinking chlorinated tap water is to invest in a home filtration system. There are many different kinds to choose from! Water is the essence of life. Invest in clean water for yourself, your family, and your pets.

In the following paragraphs, I recommend two different types of water filters with affiliate links. I’m recommending these filters because, as a water operator and a health nerd, I think they are fantastic options. If you purchase through the links, I will earn a commission.

Countertop Filter for Chlorine Removal

The Clean Water Machine by Aquasana sits on your countertop with no need to install! Just plug it into the wall! 

It filters fifteen more impurities than a pitcher filter does, including chlorine, microplastics, lead, pesticides, and more, while leaving beneficial minerals, like calcium and magnesium in the water. The Clean Water Machine works quickly, much faster than a slow-trickle pitcher filter. 

Do a Google search to find out what contaminants are in your tap water. Water reports are public, so you should be able to find one. The Environmental Working Group provides a convenient search bar where you can enter your zip code to find your water quality report. If your tap water has fluoride, The Clean Water Machine isn’t the best option! See the next option below for fluoride removal.

Under the Sink Filter for Chlorine Removal

The SmartFlow Reverse Osmosis filter by Aquasana fits nicely under your sink and cleans water to the highest standards! 

This filter is certified by the National Sanitation Foundation and the American National Standards Institute and “removes ninety impurities including fluoride, chlorine, microplastics, lead, arsenic, and more. The SmartFlow™ Reverse Osmosis boasts one of the highest certified contaminant removal rates of all reverse osmosis systems on the market. In fact, it’s certified to reduce 89 more contaminants than Amazon’s top-selling RO system is certified to reduce.”

Reverse osmosis filters are so powerful, they remove good minerals too. As a water operator, I learned that drinking pure RO water can result in the water pulling minerals from your body! That’s why the SmartFlow Reverse Osmosis filter re-mineralizes your water after filtering it. Aquasana thought of everything when they invented this bad boy!

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