The great debate about chlorination versus other methods of disinfection has still not subsided, at least not in the developed part of the world. Chlorinated water has been blamed for causing all kinds of health problems from skin rashes to hair loss to cancer. A search on the Internet will bring one in touch with a multitude of people who attribute chlorine to their health condition, including miscarriages.

Trihalomethanes (THMs) are only one subgroup of the many disinfection byproducts (DBPs) formed during chlorination. THMs are formed during the treatment process when chlorine reacts with organic content in the untreated water. Some epidemiological studies have shown an association between long-term exposure to THMs and bladder cancer.

The chlorine lobby, on its part is equally emphatic in declaring that chlorine plays a paramount role in protecting the masses from dangerous pathogens. After all, it was chlorine which single-handedly combated typhoid and cholera, those killer diseases which once blighted civilisations and reduced life expectancies.

As for byproducts such as THMs, the chlorine lobby believes that there is no conclusive link between THMs and detrimental health effects. “The health risks from these byproducts at the levels at which they occur in drinking water are extremely small in comparison with the risks associated with inadequate disinfection. Thus, it is important that disinfection not be compromised in attempting to control such byproducts,” quotes the Chlorine Chemistry Council in its website. However, it stresses that all attempts must be made to reduce such unintended byproducts. In fact, in the US, the EPA has been regulating DBPs in its drinking water from 1979. Generally, the best approach to reduce DBP formation is to remove natural organic matter precursors prior to disinfection.

Despite whatever the chlorine lobby says, a number of alternative methods of disinfection have been growing in popularity – chief among them being Ultraviolet (UV) Radiation and Ozonation. Home filters incorporating activated carbon, which remove chlorine have reaped rich harvests.

UV disinfection has been in vogue since 1920, mostly in Europe. Its most attractive feature is that it does not add chemicals and there are no byproducts. Today there are a hundreds of UV plants mostly in Europe and North America. A number of companies such as Hanovia, Trojan Technologies and Wedeco are involved in the manufacture of UV equipment.

Ozone has also been widely used to disinfect water and wastewater due to its strong biocidal oxidising properties. Both ozone and UV can be used for inactivation of viruses, giardia, cryptospordium, bacteria and other microbial contaminants. Ozone has the additional benefits of taste, odour and colour removal. Recent research has also found that when ozonation is combined with UV, there is a synergistic effect.

In developing countries, there still appears to be no alternative for chlorination. Chlorine continues to offer the cheapest form of disinfection and is the foremost bulwark in the war against waterborne diseases. It is chlorine which provides the longest residual effect when all others fail.

For those living in Asia, there is little escape from the bitter taste of chlorine. Unless they can afford expensive water filters. As for me, I’d rather have coconut water whenever I can.


  1. An excellent thought provoking article. We have seen in the past how other chemicals (PCB) has adversely impacted the health of human beings. Thanks for bringing this to the attention of the public.

  2. On chlorine and disinfection: The biggest drawback to the alternatives to chlorine is that they do not leave a residual in the water. This is an extremely important factor as there are a number of ways in which water can be heavily contaminated in the distribution system. It is why every well organised water utility checks to ensure that there remains a residual in the water at the farthest point in their systems – and why you can sometimes taste the chlorine elsewhere in the system. For obvious reasons, this factor is even more important in developing countries where the system may not be well maintained – and water may be supplied intermittently.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s