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Boiling is considered the world’s oldest, most common, and one of the most effective methods for treating water. If done properly, boiling kills or deactivates all bacteria, viruses, protozoa (including cysts) and helminths that cause diarrheal disease.
Pathogens are killed when the temperature reaches 100 degrees Celsius. In high-lying areas, where the boiling temperature of water can be as low as 80 degrees Celcius, a longer boiling time is necessary to kill all pathogens.
==History and social context==
==Suitable conditions ==
{{Potential_Treatment_Capacity_table
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==What is boiling?Technical specification==Boiling is considered the world’s oldest, most common, and one of the most effective methods for treating water. If done properly, boiling kills or deactivates all bacteria, viruses, protozoa (including cysts) and helminths that cause diarrheal disease.
==How Does It Remove Contamination?==Pathogens are killed when the temperature reaches 100 degrees Celsius. In high-lying areas, where the boiling temperature of water can be as low as 80 degrees Celcius, a longer boiling time is necessary to kill all pathogens. Operation==Operation==
Water is heated over a fire or stove until it boils. Different fuel sources can be used depending on local availability and cost (e.g. wood, charcoal, biomass, biogas, kerosene, propane, solar panels, electricity).
Water bubbling as it boils provides an easy to recognize visual indicator and does not need a temperature gauge.
Pathogens are killed when the temperature reaches 100 degrees Celsius. Boil water for 1 minute and add 1 minute per 1000 metres of elevation. Boiled water should be kept in the pot covered with a lid until it is consumed.
Recommended boiling times vary between organizations. The World Health Organization recommends that water be heated until it reaches the boiling point (WHO<ref>[[#WHO|WHO]]</ref>). The Centers for Disease Control and Prevention, recommends a rolling boil of 1 minute, to ensure that users do not stop heating the water before the true boiling point is reached (CDC, 2009).
Recontamination of boiled water is a major problem. Water is often transferred from the pot into dirty storage containers which then make it unsafe to drink. It is recommended to store boiled water in its pot with a lid to reduce the risk of recontamination.
Some people believe that boiled water tastes flat. This is caused by dissolved oxygen escaping from the water as it boils. This can be reduced by vigorously stirring or shaking cooled water to increase its dissolved oxygen content. Almost all households have the equipment required to boil water.
Boiling requires fuel supply and takes time. Users may not consistently boil water to conserve fuel and save time.
====Treatment efficiencyEfficiency====
{{Treatment_Efficiency
|lab:bacteria=Up to 100%
}}
==Operating criteria==Maintenance====Pathogens are killed when the temperature reaches 100 degrees Celsius. Boil water Pots used for 1 minute and add 1 minute per 1000 metres of elevation. Boiled water should boiling may need to be kept in the pot covered with a lid until it is consumedreplaced.
==Robustness==Manufacturing====Almost all households have Needed materials are fuel (e.g. wood, charcoal, biomass, biogas, kerosene, propane, solar panels, electricity, a pot and a lid. Labour is needed for the equipment required to boil waterregular collection of some fuels (e.g. wood, charcoal, biomass).
====Estimated lifespanLifespan====
On-going requirement for fuel. Pots used for boiling need may need replacement.
==Cost==
Note: Program, transportation and education costs are not included.
==Country experiences== ==Manuals== ==Movies== ==External linksLinks==
[http://www.cawst.org CAWST (Centre for Affordable Water and Sanitation Technology)]
*<cite id=WHO>World Health Organization. [http://www.who.int/entity/household_water/resources/emergencies.pdf Household Water Treatment and Safe Storage Following Emergencies and Disasters: South Asia Earthquake and Tsunami]. Available at: [www.who.int/household_water/en/]</cite>
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