Household Water Treatment and Safe Storage Factsheet: Source ...
Household Water Treatment and Safe Storage Factsheet: Source ...
Household Water Treatment and Safe Storage Factsheet: Source ...
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<strong>Household</strong> <strong>Water</strong> <strong>Treatment</strong> <strong>and</strong> <strong>Safe</strong> <strong>Storage</strong><br />
Fact Sheet: Chlorine (Sodium Hypochlorite)<br />
Key Data<br />
Inlet <strong>Water</strong> Criteria<br />
Low turbidity<br />
pH between 5.5 <strong>and</strong> 7.5; disinfection is unreliable above a pH of 9<br />
<strong>Treatment</strong> Efficiency<br />
Bacteria Viruses Protozoa Helminths Turbidity<br />
Laboratory High 4 High 4 Low 4 Ineffective5 –<br />
Moderate 6 0%<br />
Field Not available Not available Not available Not available 0%<br />
1<br />
Bacteria include Burkholderia pseudomallei, Campylobacter jejuni, Escherichia coli, Salmonella typhi, Shigella<br />
dysenteriae, Shigella sonnei, Vibrio cholerae, Yersinia enterocolitica.<br />
2<br />
Viruses include enteroviruses, adenoviruses, noroviruses, rotavirus.<br />
3<br />
Protozoa include Entamoeba histolytica, Giardia lamblia, Toxoplasma gondii, Cryptosporidium parvum.<br />
4 CDC (2007)<br />
5 AWWA (2006) shows that chlorine is ineffective for Ascariasis lumbricoides ova.<br />
6 Mercado-Burgos et al.(1975) show moderate effectiveness for Schistosoma species. Assume moderate effectiveness for<br />
Dracunculus medinensis.<br />
<br />
Toxoplasma oocysts <strong>and</strong> Cryptosporidium parvum oocysts are highly resistant to chlorine<br />
disinfection (CDC, 2007). Chlorine alone should not be expected to inactivate these<br />
pathogens.<br />
Operating Criteria<br />
Flow Rate Batch Volume Daily <strong>Water</strong> Supply<br />
Not applicable Unlimited Unlimited<br />
Need to follow manufacturer’s instructions for specific sodium hypochlorite products<br />
Required dose <strong>and</strong> contact time varies with water quality (e.g. turbidity, pH, temperature)<br />
Very turbid water should be sedimented or filtered prior to chlorination<br />
Use a 30-minute minimum contact time<br />
For high pH water (>9), the contact time should be increased (Lantagne, 2009)<br />
The contact time should be increased to 1 hour when the temperature is between 10˚ <strong>and</strong><br />
18˚C. It should be increased to two or more hours when the temperature falls below 10˚C.<br />
Robustness<br />
<br />
<br />
<br />
<br />
<br />
<br />
Free residual chlorine protects against recontamination<br />
Most users cannot determine the dosing quantity themselves; proper use requires following<br />
instructions from the manufacturer<br />
Users may use less than the recommended dose to save money<br />
Requires supply chain, market availability <strong>and</strong> regular purchase<br />
Requires quality control process to ensure product reliability<br />
Sourcing suitable plastic containers to manufacture chlorine solutions can sometimes be a<br />
challenge<br />
Estimated Lifespan<br />
<br />
<br />
Chlorine deteriorates over time, especially in liquid form<br />
Liquid chlorine expiry is 6 weeks without pH stabilization <strong>and</strong> 1 year if the pH of the solution is<br />
above 11.9 (Lantagne et al., 2010)