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Sodium hypochlorite is one form of chlorine used for water disinfection. It can be manufactured in most locations since it can be obtained through the electrolysis of salt water. Bottles can be purchased for household water treatment from many manufacturers in various sizes. Chlorine concentrations range from 0.5 to 10% and each product should have its own instructions for correct dosing of contaminated water. Liquid household bleach also contains sodium hypochlorite, and is widely available.
Chlorine forms hydrochloric acid when added to water which causes chemical reactions which deactivate contaminants and reacts through oxidization with micro-organisms, organic matter, manganese, iron and hydrogen sulphide.
'''Three things can happen when chlorine is added to water:'''
#Some chlorine reacts through oxidization with organic matter and the pathogens in the water and kills them. This portion is called consumed chlorine.
Chlorine began to be widely used as a disinfectant in the early 1900’s. It revolutionized drinking water treatment and dramatically reduced the incidence of waterborne diseases. Chlorine remains the most widely used chemical for water disinfection in the United States.
===Suitable conditions===
Unlimited amounts of water can be processed at a time, depending on the amount of active chlorine.
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===Construction, operations and maintenance===
There are several different brands of chlorine products that have been manufactured specifically for household water treatment. Each product should have its own instructions for correct dosing and contact time.
The contact time should be increased to 1 hour when the temperature is between 10˚ and 18˚C. It should be increased to two or more hours when the temperature falls below 10˚C.
<!--See CAWST’s Technical Brief on Chlorine Disinfection of Drinking Water for information on how to determine the chlorine dose and contact time using household bleach. -->
Metering pumps as [[Dosatron]] can be used for proportional dosing .
====Manufacturing====
It can be manufactured in most locations since it can be obtained through the electrolysis of brine. Bottles can be purchased for household water treatment from many manufacturers in various sizes
A recent meta-analysis showed that chlorine reduces the risk of child diarrhea by 29%
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There are many producers of chlorine solutions all around the world. <!--See CAWST’s Sodium Hypochlorite Product Sheets for further details.-->
===Costs===
{{Treatment_Cost
|CapCost=US$ 0
Note: Program, transportation and education costs are not included.
===Field experiencesExperiences===The following project(s) utilize chlorine.<br>{|style="border: 2px solid #e0e0e0; width: 20%; text-align: justify; background-color: #e9f5fd;" cellpadding="2"|- style="vertical-align: top"|[[Image:akvorsr logo_lite.png|center|60px|link=http://akvo.org/products/rsr/]]|- style="vertical-align: bottom"|[[Image:project 810.png |thumb|center|140px|<font size="2"><center>[http://wash-liberia.akvoapp.org/en/project/810/ RSR Project 810]<br>Improved Water Sanitation and Hygiene</center></font>|link=http://wash-liberia.akvoapp.org/en/project/810/ ]] |} <br>
===Manuals, videos, and links===* [http://fieldresearch.msf.org/msf/bitstream/10144/618835/1/FRC+Op+Guidance+Briefing+Note+%28Nov+2016%29.pdf Operational Guidance Briefing Note: Evidence-based Free Residual Chlorine (FRC) Targets]
*[http://www.cawst.org CAWST (Centre for Affordable Water and Sanitation Technology)]
*[http://www.enpho.org/drinking_water_quality.htm Drinking water quality information from Environment and Public Health Organization (ENPHO)]*[httphttps://www.cdc.gov/safewater/publications_pages/pubs_chlorinechlorination.htm html Centers for Disease Control and Prevention]
*[http://www.psi.org/child-survival Population Services International (PSI)]
*[[Solution_of_the_week_3|Akvo water solution of the week 3]]
==Footnotes=References===
<references/>
===Acknowledgements===
This article is based on a factsheet from [http://www.cawst.org/ Centre for Affordable Water and Sanitation Technology (CAWST)], which is gratefully acknowledged.
