Chlorine is added to treated water at the Joyce Road and Oropi Water Treatment Plants to kill germs in the pipes which carry the water to your home. This practice is widespread in New Zealand and many other countries and has been done for decades.

Some promoters of home water treatment devices use emotive language to scare people into purchasing their products referring to chlorine as a "poison".  Do not be alarmed!

It is true that the chlorine can combine with non-toxic chemicals which can naturally occur in water to form compounds that may cause cancer.  But not all organic compounds containing chlorine cause cancer.  So just adding chlorine to organic compounds in water does not necessarily produce a carcinogen (cancer-causing chemical).

The most common by-products of the disinfection process are called trihalomethanes (pronounced, try-halo-me-thanes). Informed opinion on the risks of the disinfection by-products is that any effects to humans "are very small and difficult to measure in comparison with the risks associated with inadequate disinfection".

Do not be frightened into purchasing a home water treatment unit on health grounds.  Tauranga has the highest level of water quality rating from the Ministry of Health.  The microfiltration systems at the Joyce Road and the Oropi Treatment Plants provides a physical barrier against Giardia and Cryptosporidium to keep them out of the water supply.  Tests have also shown that the level of trihalomethanes in Tauranga water is low.

Some people object to the taste of chlorine in water.  Most, if not all of the taste, can be removed by boiling the water for five minutes.  But remember, once you have reduced the level of disinfectant, you should treat the water like any other food which can be contaminated. Keep it covered in the fridge and use it as quickly as possible.

* J.M. Symons (1997), Plain Talk About Drinking Water, American Water Works Association, 3rd Edition, 238pp