Why is Chlorine Present in Drinking Water?

Why should chlorine be present in our drinking water? It is for very good reasons, as the treatment and distribution of safe drinking water are considered by the U.S. Centers for Disease Control (CDC) as one of the major public health achievements of the twentieth century.

Towards the end of the nineteenth century it was found in London, UK, that water from a city well that had spread infectious diseases ceased to be dangerous after having been treated with chlorine.

Then in a few years the practice of water treatment was adopted by most of the civilized world as a means of protecting public health.

Up to those times drinking wine instead of water of dubious quality was the best assurance against illness, for those who could afford the expense.

Disinfecting the drinking water for human and animal use ensures that it becomes free of active microorganisms causing serious and life-threatening diseases, such as cholera and typhoid fever.

Chlorine is effective in killing most pathogenic bacteria and viruses. Chlorine however is not effective in killing certain protozoa like cryptosporidium.

The term chlorine refers to the chemical element Cl that exists as a poisonous yellow gas, irritant of the respiratory tract even at low concentration. As it is a very active element it is found in nature mostly as a compound, of which common table salt, sodium chloride (NaCl) is an example.

Chlorine gas is soluble in water. A common household product, bleach, is a water solution containing about 3 to 6% of sodium hypochlorite (NaOCl). This product too can be used to disinfect water in case of need.

Additional chlorination effects are the removal of iron and manganese and the residual property of continuing to hinder pathogen reproduction during the long way from the treatment facility to the house tap.

Is it safe to human health to drink chlorinated water?
It depends on whom you ask.

Some studies point to increased risk on health, while others show no additional risk.

It is generally recognized that drinking water chlorination is the process of choice for eliminating most of the life-threatening pathogens possibly present in the water reaching treating plants.

Some research efforts concentrating on the effects of certain by-products of the treatment, seem to suggest that substances like Trihalo-methanes (THM) have the potential to induce cancer in individuals as they do in laboratory animals when supplied at very high levels.

However it is commonly accepted that their presence in treated water in minimal quantities is far from threatening.

EPA regulates how much of these substances are tolerated in chlorinated water for safe use. The current EPA regulations establish a limit of 80 parts per billion (ppb), for THMs based on the annual average of eight distribution system monitoring locations.

Industrial and commercial sources, with deep interests in the use of chlorine and its derivatives, vehemently insist that independent medical sources failed to find statistically relevant results connecting chlorine with development of cancer diseases.

Other sources interpreting more strictly the results of certain research, seem to find concrete demonstration of the dangerous effects on health of chlorinated water.

Until more definitive research will authorize to settle the dispute by defining ways to sort the probable outcome of illness course according to additional contributing factors, it is possibly quite safe to assume that the present official standing of appointed authorities on water quality should be accepted except perhaps in unusual circumstances.

All sources agree that the benefits of chlorination for eliminating the presence of pathogens, are much greater than the minimal risk still remaining, if at all, relative to residual by-products.

The other existing means for obtaining a comparably safe result (ozonation, Ultraviolet light treatment, and use of chlorine compounds like chloramines and chlorine dioxide) are more expensive and do not provide sufficient advantages to promote their substitution.

It is suggested by professional experts that installing a suitable home filter at the point of use removes the nuisance of chlorine and byproducts from the drinking water.