Chlorine for safe water

Chlorine was first used in drinking water in the late 19th century to control the spread of water-borne diseases such as typhoid, cholera, dysentery and gastro-enteritis, which have killed more people than all the wars in history. Fighting these diseases remains vital today.

Providing quality drinking water is a major challenge in many areas of the worldThe World Health Organization estimates that each year, more than three million people still die as a direct result of drinking unsafe water, of which 1.7 million from diarrheal diseases.
Read more about the United Nations Health Organization's Global Outlook Alert & Response Network on

Today, 783 million people do not have access to safe water sources (figure joint Report UNICEF/United Nations, April 2012). At the 2002 World Summit on Sustainable development, the Global Community committed to halve by 2015 the proportion of people without access to safe and healthy drinking water.

The world seems to be well on track to meet the drinking water target and even is five years ahead, as reported by a member of the American Water Quality and Health Council in April 2012. This is to a large extent thanks to water chlorination and the use of sustainable PVC piping for clean water transport. But, given rapid population growth, it is estimated that over 780 million people could still without safe drinking water by 2015. Read here the WHO press release on this issue.

Chlorine acts as a powerful disinfection agent when used either on its own or as sodium hypochlorite (bleach). Added to water in minute quantities, it quickly kills bacteria and other micro-organisms, by chemically oxidizing their cell walls.  Chlorine has the major advantage of ensuring clean water right up to the tap, whereas the action of other disinfectants - such as ozone, ultraviolet light and ultra filtration - is only temporary.

In addition to purifying water, chlorine helps remove tastes and odours, controls the growth of slime and algae in mains pipes and storage tanks, and helps to remove unwanted nitrogen compounds from water. Today, more than 90% of Western Europe's drinking water is chlorinated.

Proven life saver

Many events testify to the importance of chlorine in water purification:

  • In the US, annual deaths from cholera totalled 25,000 in 1900. By 1960, this figure had fallen to fewer than 20;
  • In 1991, a misinterpretation of US law resulted in a voluntary suspension by Peru's government of chlorination of water supplies. The resulting cholera epidemic spread to neighbouring countries causing 1,000,000 cases of cholera and more than 10,000 deaths;
  • In 1986, 4,000 people in Tenerife were hospitalised due to water contamination which followed the temporary withdrawal of chlorine for disinfection.
  • But even today, the world is fighting killer diseases like cholera in many regions, for instance in Africa. Read here our webpage about this situation.

A range of chlorine compounds - including ferric chloride (FeCl36H2O) and hydrochloric acid (HCl) - are used to purify waste water and sewage.

Swimming pools and chlorine are a fine matchIn the home, chlorine-based products are used in laundry bleach, dishwasher detergents, scouring powders and paper towels, and as all-purpose disinfectants to kill common germs (including Staphylococcus, Salmonella, Pseudomonas and athlete's foot fungus).

Swimming remains a very popular, healthy leisure pastime thanks in part to the benefits of chlorine. Disinfectants based on this element keep swimming pool water safe by killing a range of dangerous microbes which could otherwise threaten health.

 Last update: 05/2012