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[[Image:safe_water_systems_icon.png|right]]
[[Image:Household bleach.jpg|Woman using chlorine from household bleach to disinfect water]]
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.
#Excess chlorine that is not consumed or combined remains in the water. This portion is called free residual chlorine (FRC). The FRC helps prevent recontamination of the treated water.
• Proven reduction of most bacteria and viruses in water• Residual protection against contamination
{{procontable | pro=
- Kills bacteria nad viruses effectively <br>
- Residual chlorine protects water from recontamination <br>
- Acceptability to users because of ease-of-use <br>
- Proven health impact <br>
- Scalability <br>
- Low cost <br>
- Plenty of testing and field assessments <br>
- Local familiarity with product <br>
| con=
- Requires clear water to be most effective Lower disinfection effectiveness in turbid waters contaminated with organic and some inorganic compounds <br>
- May not be effective at killing parasites <br>
- Taste and odor are unacceptable to some <br>
- Chlorine forms complex compounds with organic material which may be detrimental to health over time. <br>
- Chlorine degrades over time. <br>
- Contact time is required. <br> - Most users cannot determine the dosing quantity themselves; proper use requires simple instructions from the manufacturer <br>
- Chemical dosage required varies with water quality<br>
- Chlorine needs to be purchased continuously <br>
- Chlorine can be hazardous if used improperly . Requires quality control process to ensure product reliability - Chlorine fumes and contact with skin are hazardous <br>- Concern about the potential long-term carcinogenic effects chlorination by-products <br>- Relatively short shelf life <br>- Uncertain concentration and shelf life, susceptibility to gaps in supply chain, high transportation costs, and difficulty in dispensing precise quantities <br>
}}
==History and social context==
Some users complain about the taste and odour that chlorine may cause in water. Chlorine reacts with organic matter naturally present in water to form by-products such as trihalomethanes (THMs), which are potentially cancer-causing. Lantagne et al. (2008)<ref>[[#lantagne08|Lantagne et al. (2008)]]</ref> indicate that THM levels produced during household chlorination may fall below World Health Organization (WHO) guideline values.
The use of household bleach products for household water treatment is not recommended in the absence of ongoing quality control testing, due to poor quality control of most sodium hypochlorite bleaches. If household bleach is used, the concentration should be regularly tested and an appropriate dosage strategy (2 mg/l for waters of turbidity 0-10 NTU, 4 mg/L for water of turbidity 10-100 NTU) should be developed by the recommending organization.
{{Potential_Treatment_Capacity_table
- Viruses<br>
- Most Protozoa<br>
- Helminths<br>- Ammonium <br>
| not=
- Cryptosporidium oocysts<br>
- Chemicals<br>
- Taste, odour, color
| process=DisinfectionChemical disinfection
| watcrit=
Low Turbidity<br>
====Operation====
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.
Liquid household bleach products are also commonly used to disinfect drinking water. The strength of the product must be known to calculate how much bleach is needed to disinfect a given amount of water.Commercial bleach from the United States requires users to add 3-5 drops to 5 gallons of water. Some bleach bottles come with a top that dispenses by drops
The effectiveness of chlorine is affected by turbidity, organic matter, temperature and pH.
====Manufacturing====
====Estimated Lifespan====