Risks Of Having Too Much Chlorine In Swimming Pools Or Hot Tubs

People dive into swimming pools at any time of the day to rest their tired body from all day of work. Few laps can help improve the overall fitness and body goals. Furthermore, the mind can meditate and escape reality momentarily whenever one is on the water.

The popularity of swimming pools and hot tubs dated many years ago. The concept of ‘The Great Bath’ started as early as the 3rd millennium BC at Mohenjo-Daro (now known as Pakistan). People gather at the place to clean their body and socialize with people.

Through the years, the great bath has changed. The interior/ exterior design become safer and inviting. People have also discovered chlorination to make the water clean.

However, there are risks of having too much chlorine in the water. Thus, this article will discuss what chlorine is and its advantages. Next, this will tackle the risks (health, environmental, and other concerns) of too much chlorine. Lastly, this will give tips on how to prevent or deal with chlorine overexposure.

Chlorine: One Of The Lightest Halogens

Chlorine is a chemical element and it is one of the lightest halogens. Considered as one of the fundamental blocks of matter, this element occurs naturally. It can be found in the rocks of the continents of the Earth and on the salty oceans. Indeed, it is essential for the growth of the plants and animals.

At room temperature, it is a yellow-green gas. Big companies produce it from brine using electrolysis. With the high oxidizing potential of this element, it has led to several products like disinfectants and bleaches.

Millions of people around the world turn on to chlorine to produce clean drinking water. Apart from this, chlorine is being used in swimming pools and hot tubs to keep it sanitary.

Brief History Of Pool Chlorination

In the United States, the first public swimming pool opened in 1887 in Brooklyn, Massachusetts. During these days, the water in the pools was filtered to keep them clean. Apart from this, owners change the water frequently.

Then, in 1890’s, cheap electricity become available coming from the central generating stations. Commercial chlorine was produced as a by-product of the electrolytic production of sodium hydroxide. In 1908, chlorine was used in treating potable water at Jersey City’s Boonton Reservoir in Boonton, New Jersey.

After treating drinking water, engineers had also thought of using it for filtering swimming pools. At that time, many people have recognized the importance of pools for physical fitness and health.

Thus, in 1910, engineers have sterilized a pool at the Brown University. The Colgate Hoyt Pool can be filled by 70,000 gallons of water. But this much water was cleaned successfully using chlorine by a student named as John Wymon Miller Bunker.

Bunkers added hypochlorite of lime to 2 liters of water in the pool. It has a concentration of 1 ppm. Thereafter, the water in the pool remained sterile for four days.

In the middle of 20th century, the compounds chlorine and cyanuric acid became widely available in cleaning swimming pools. These functions as a source of hypochlorous acid which is a sanitizing agent. When used correctly, it will provide long-lasting chlorine and will not affect the pH level of the water.

Nowadays, residential pool owners utilize a combination of techniques to clean the water. They use chlorine with isocyanurates which are formed into tablets. This will ensure long-term and steady chlorination. Also, some people use calcium hypochlorites for shock treatments.

How Does Chlorine Clean Pools Or Tubs?

Chlorine is being used to keep the pools and tubs free of harmful bacteria. But, how does this chemical do the magic?

It performs its wonders through a simple chemical reaction. The solution one pours into the water can break down various chemicals, such as hypochlorite ion (OCI-) and hypochlorous acid (HOCI).

These two chemicals can kill microorganisms by attacking the lipids in the cell walls. Also, it destroys the structures and enzymes in the cell and makes it harmless.

Once the HOCI and the OCI- are done cleaning the swimming pools or tubs, it combines with other chemicals or breaks down into single atoms. With this, the chlorine will be harmless. As it breaks down, one must keep adding chlorine in the pool and let the sunlight speed up the process.

Indeed, chlorine can clean up pools and make it enticing to children and adults alike.

Risks Of Having Too Much Chlorine

The Centers for Diseases Control and Prevention states that the chlorine levels of the swimming pools and tubs must be from 1.0 to 3.0 ppm only. If it exceeds this amount, then, there could be possibly physical and even ecological risks. Here are some of it:

Health Risks

Problems In Eyes And Skin

Usually, the excessive chlorine levels in the water are caused by equipment malfunction and human error. Over-chlorination can cause swimmers to experience moderate to severe irritation of the eyes.

Also, as they inhale the water, they can experience a burning sensation in the nasal passages plus the mouth.

In addition, some people can have skin rashes whenever the pH level of the water becomes unbalanced. On a scale of zero to 14, the pH level must be 7 to be balanced. If it’s below 8 or 7, then the water condition may pose a possible danger to the skin and membrane tissues.


Chlorine can affect the hair by direct chemical reactions. It can change the hair components, physical properties, electrical charge of minerals, and react with various minerals.

The direct chemical changes can cause the natural color of the hair to change. Sometimes, blonde hair can turn into darker colors.

Also, chlorine can remove the natural oils that cover the hair. With this, the flexibility and shine of the hair diminish. It also makes it susceptible to any mechanical damage.

In the long run, the hair becomes weak and there are more split-ends. It can affect the hair cuticle, making it rough, and be prone to breakage.

Respiratory Illnesses 

Clients can experience severe lung irritation from over-chlorinated hot tubs. Whenever the pools and hot tubs are over-chlorinated, it means that it is poorly maintained. If the chlorine interacts with blood or feces in the water, then it can produce a toxic environment in the pool.

As such, it can lead to various respiratory illnesses like asthma, pneumonia, and fibrosis.

Dental Health

The acidic pool water can damage the dental health as well. Swimmers oftentimes experience this problem. As they spend more hours in the pool, they can have greater exposure to acidic water. Some of the dental health risks are tooth decay, exposed tooth root, worn fillings, and gum disease.

Digestive Issues

When one accidentally drinks chlorinated water in large amounts, then he is at risk of having digestive problems. The high chlorine in the tubs or pools can destroy the intestinal flora. With this, the ability of the stomach to effectively absorb and process nutrients will be affected.

As such, the absorption of minerals and minerals will change and make the body become vulnerable to other diseases.

Thyroid Processes

Excessive chlorine can cause health problems in the long run. For instance, it can interfere with the thyroid’s processes. Soon, it can possibly lead to the development of hypothyroidism.

The thyroid glands located in the neck controls the rate of hormone levels. Taking in water with too much chlorine can block the iodine receptors in the thyroid gland. Then, it can reduce the production of the iodine-containing hormone in the body.


There are various studies and research projects that determine the direct relationship between over-chlorinated water and cancer.

For example, the Oak Ridge Associated Universities conducted a study that states if one drinks chlorinated water for 15 years, he can have high chances of developing colon cancer.

On the other hand, the Journal of the National Cancer Institute states that over-exposure to chlorine can increase the chances of having bladder cancer of up to 80%.

Lastly, a study by the Medical College of Wisconsin in 1992 found that rectal and bladder cancers are linked to the excessive amounts of chlorine in public pools and tubs.

Susceptibility To Infections

A surplus of chlorine can kill the good bacteria in the body and ruin the immune system. And when the body deteriorates, it becomes more susceptible to infections.

Environmental Risks

Over chlorination can have a significant impact on the environment. When the pool with the chemicals evaporates, it can contribute to the production of the greenhouse gases.

Also, the discharging and draining of the chemically treated water can cause problems in the waterways if it’s not done correctly.

Finally, too much chlorine can affect other living organisms such as the plants and the animals whenever the water is flushed out of the tubs and swimming pools.

Tips On How To Lower Chlorine Levels

To prevent over-chlorination of tubs and pools, the first thing to do is to test the chlorine levels. With this, owners can figure out the best option to regulate chlorine in the water.

If the level of chlorine is 4ppm or slightly high, the easiest way to do is to not use the pool for an hour or two. But if its higher than 4ppm and the pool is needed asap for the party, then an intervention is needed.

However, there are four options that one can choose in dealing with over-chlorination:

Don’t Add Chlorine

If the chlorine reading is a little higher than 3ppm, stop adding more on it.

Turn off the chlorinator or the chlorine feeder. Remove the chlorine floater from the pool. Also, take away the chlorine tablet from the skimmer.

Make sure not to add more chlorine to the water whenever the swimmers have already jumped in the tubs or pools.

Uncover The Pool And Let The Sun Shine On The Water

If the pool is needed in few hours and the chlorine swims in the water, uncover the pool and let the sun shine on it. The ultraviolet rays of the sun can destroy the chlorine. It can deplete about 90% of the chlorine level in just 2 to 3 hours. By this time, all the bad bacteria in the pool will be cleaned and ready for swimmers.

Add Some Chlorine-Neutralizing Chemical In The Water

A quick fix in over chlorination in the water is using another chemical. But as with most quick fixes, this has downsides and caveats too.

The two most popular chemicals to reduce chlorine in the water are Sodium Sulfite and Sodium Thiosulfate. Meanwhile, the alternatives are Sodium Metabisulfite and Sodium Bisulfite. These chemicals are available in big bags and are cheaper than those products in the bottles.

In using the chemicals, see to it that the directions are being followed. As the filter runs, pour the measured dose in the pool skimmers. Usually, 60 grams of the chemical will reduce the chlorine by 1ppm. This is true for pools with approximately 41,000 liters of water.

Gradually add the neutralizers and make sure not to add too much at once because all of the chlorine will be destroyed. Test the pH level before and after adding the chemicals to make adjustments if needed.

Replace Some Of The Pool Water

Replace some of the existing water in the tub or in the pool. This option might be a natural process of dilution, however, it is not the quickest fix that one can have.

If owners have DE or sand filters, the fastest way to solve the over-chlorinated pool water is to backwash. However, refilling the pool again with fresh water to dilute excessive amounts of chlorine can take time.

On the same note, it can cost more money when it comes to paying water bills. Freshwater can also make the alkalinity, pH level, and calcium hardness not to work. As such, make sure that the water is tested and adjusted accordingly as one is done by topping up the pool.


In a nutshell, jumping in the pool or tub with chemicals can be nerve-wracking for some. However, chlorine-based cleaning solutions are essential in making the water clean and safe. It kills harmful bacteria and other microscopic organisms from clouding the water. Without the aid of chlorine, the pool water can become a good source of water-borne infections.

However, too much chlorine is harmful to people too. It threatens the health and the environment and its effects can be devastating.

One must note that chlorine must be regulated accurately. There is no room for human or machine error because the life of the people is at risk. Proper training is important, especially for those who maintain the tubs and pools, so as not to endanger the lives of many people.

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