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Household water treatment and safe storage
- World Health Organization report
Treatment technologies
A variety of candidate technologies for treatment of household water
have been described and many are widely used in different parts of the
world. The technologies to improve the microbial quality of household
water and reduce Water-born diseases include a number of physical and
chemical treatment methods. The physical methods, include boiling, heating (fuel and solar), settling, filtering, exposing to the UV
radiation in sunlight, and UV disinfections with lamps. The chemical
methods include coagulation-flocculation and precipitation, adsorption,
ion exchange and chemical disinfection with germicidal agents (primarily chlorine).
Some water treatment and storage systems use chemicals and
other media and materials that can not be easily obtained locally at
reasonable cost and require relatively complex and expensive systems and
procedures to treat the water. Such systems may be too inaccessible,
complex and expensive to employ for treatment and storage of household water in some places and settings.
The efficacy of some treatment methods to physically remove particles
(turbidity) and microbes or to inactivate microbes in household water
has been documented, primarily for indicator bacteria. Some treatment
methods, such as boiling, solar disinfections, UV disinfections with
lamps, chlorination and the combined treatments of chemical coagulation-filtration and chlorination have been evaluated for
reductions of bacteria, viruses and in some cases protozoans. However,
the ability of some of these methods to remove or inactivate a wide range of known waterborne pathogens has been inadequately investigated
and documented.
Treating turbid water
Studies have shown that improving the microbiological quality of
household water by on-site or point-of-use treatment and safe storage in
improved vessels reduces diarrheal and other waterborne diseases in communities and households of developing as well as developed countries.
The extent to which improving drinking water quality at the household
level reduces diarrheal disease probably depends on a variety of technology-related as well as site-specific environmental and
demographic factors that require further investigation, characterization
and analyses. Reductions in household diarrheal diseases of 6-90% have
been observed, depending on the technology and the exposed population and local conditions.
The most promising and accessible of the technologies for household
water treatment are filtration with ceramic filters, chlorination with storage in an improved vessel, solar disinfections in clear bottles by
the combined action of UV radiation and heat, thermal disinfection (pasteurization) in opaque vessels with sunlight from solar cookers or
reflectors and combination systems employing chemical coagulation-flocculation, sedimentation, filtration and chlorination.
All of these systems have been shown to dramatically improve the
microbiological quality of water. Further development, refinement, implementation, evaluation and
comparison of household water treatment and safe storage technologies is
both justified and encouraged. |
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