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.
The 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
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
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
- In the US, annual deaths from cholera totalled
25,000 in 1900. By 1960, this figure had fallen to fewer than
- 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
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.
In 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
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