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Why is Chlorine used to treat tap water?


Why is Chlorine used to treat tap water?

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What is chlorine?

Chlorine is a word we all hear a lot, but before we go in depth as to how it effects your water and body let us look at what it is. A commonly found element, with the symbol of CI and atomic number 17, it is often found combined with other elements. For example, the most common compound, is salt, sodium chloride to be precise, but other compounds are not as friendly.

A toxic gas, it attacks the respiratory system, eyes, and skin. It is detectable by smell at 3 parts per million. Coughing and vomiting may occur at 30 ppm and lung damage at 60 ppm. About 1000 ppm can be fatal after a few deep breaths of the gas, scary stuff.

After hearing that you might be surprised but chlorine is one of the most widely used disinfectants found in homes, industrial cleaning, and health care facilities. It is used to disinfect swimming pools, spas, to disinfect equipment in restaurants, and even to sterilise baby feeding bottles.

With sanitation being big part of our lives in 2021, you should also know that it is used in a wide variety of sanitation. One of those is water, and wastewater treatment processes, both as a disinfectant and as an oxidant.

Chlorine in water

Why is it added to drinking water?

Simply put it is effective in killing many types of bacteria, viruses, and parasites. Some of these include Escherichia coli, listeria, salmonella, and other micro-organisms. Since chlorine has been added to water supplies there has been a drastic reduction in water-borne infections. Such as cholera, typhoid fever, and dysentery. It is simple to use, is effective in killing bacteria, and most importantly inexpensive. These are the reasons for it being the go-to for treating large amounts of water.

The inexpensive factor plays a large role in the reason it is still used today in water treatment. With the advancements in technology many countries have sought to move away from chlorine. The best example of this is The Netherlands. Up until the mid-1970s, like majority of countries around the world they relied on chlorine to treat water, after discovering that it produced trihalomethanes (more on these later) the country put the time and infrastructure in place to reduce its reliance on chlorine. In 2005 The Netherlands successfully moved away from chlorine water treatment solutions and implemented a four-point approach.

  1. Use the best available water sources
  2. Find alternatives to chlorine
  3. Prevent contamination
  4. Constant monitoring of the water quality

A major part in the success of the Dutch model is the use of physical filtration. A system of sediment filtration in combination with UV disinfection means the need to bleach the water with chlorine no longer exists.

After reading this you may questions as to why more countries to not switch to the Dutch model. The problem arises that The Netherlands is the most densely populated country in Europe, thus replacing the infrastructure required to achieve this model is financially feasible. In Australia’s case due to the spread of the population in combination with the variance in water sources makes this model an unachievable pipe dream.

Levels in Australia

Now that we understand the reasons for using such a harsh chemical to treat water, it is important to look at just how much is used. The levels found in Australian tap water are regulated by the Australian Drinking Water Guidelines. The maximum level of chlorine that may flow through your taps according to the guideline is 5mg/L, which if you own a pool may come as a surprise as you would not want to see anything much higher than 3mg/L in when you test your pool. This is of course the maximum level allowed by the Guideline, and not the levels seen in the home.

Through-out Australia most homes will see somewhere between 0.5 – 1.5mg/L, although in saying that there are areas which see numbers up wards of 2.0 – 3.0mg/L. You would not take a glass of water from your swimming pool and drink it, so why ingest those level from your tap.

Problems with chlorine

In drinking water, the most obvious problem with chlorine is that it leaves an unpleasant taste and can often have a distinct smell. Those are just the immediately noticeable problems, the real issue is often not the chlorine itself, but in fact what occurs when it reacts with other materials.

According to a Belgian study that was released in 2003, certain irritants called trichloramines are released any time chlorinated water reacts with organic materials. These trichloramines are believed to initiate a biological process that effectively destroys the cellular barriers surrounding the lungs.

“Cancer risk among people drinking chlorinated water is 93% higher than among those whose water does not contain chlorine.”

According to the U.S. Council Of Environmental Quality

Chlorine is ingested from drinking water but also a major factor is it is inhaled in showers, and although only in small amounts absorbed through our skin. It can make hair and skin feel dry after showering, the reason for this is the immune system may identify the chlorine as a “foreign invader” like a bacteria or virus and become inflamed and irritated. The chlorine can also remove the natural oils on the skin, causing it to become dry.

You may never have experienced dryness of the skin after a shower or bath but looking at those who have sensitive skin demonstrates that chlorine may play a role in the development or worsening of atopic dermatitis (the most common form of eczema). A study from the American National Library of Medicine found that the water-holding capacity of the upper layer of the skin in patients with eczema was more sensitive to free residual chlorine than patients without eczema. Although the effects of chlorine may not be immediately seen as with those with eczema, given we expose ourselves to chlorine everyday what long term effects does it have on our health?

“When chlorine enters the body as a result of breathing, swallowing, or skin contact, it reacts with water to produce acids. The acids are corrosive and damage cells in the body on contact.”

New York State Department of Health

In the long run showering and bathing in chlorinated water exposes us to even more chlorine than drinking the byproducts in the chlorinated water. Since chlorine tends to dehydrate the skin, many people find that simply removing chlorine from their bathing water can have a beneficial effect on their overall wellness.

Although a great deal of research has already taken place until we know more about how chlorinated water affects our health, it seems prudent to keep chlorine exposure to a minimum.

Removing chlorine from my water?

Fully abandoning chlorination at the source probably remains unrealistic for Australia as a whole, but once the chlorine has done its job of disinfection, the choice can be made to remove it. Whole home filtration has emerged as a cost effective and practical method of removing chlorine before it enters your home. In doing so, not only will you cut it out of your drinking water but remove it from showers and baths as well.

Our Complete Home Filtration systems are fitted with carbon filtration, which adsorbs it without leaving any negative effects on your water supply.

These filters remove 98.5% of the chlorine, which in turn returns the water to its original taste, odor and organic compound delivering clean, filtered water to every outlet in your home.



Dangers of Chlorine?:

Australian Drinking Water Guidelines:

How does chlorine in water affect my health:

Department of Health WA:

Water treatment alternatives:

National Library of Medicine:

Facts about Chlorine: