Civil Engineering Reference
In-Depth Information
16.7 Domestic water purifi cation: challenges to bring
about an integrated system
According to a WHO (2007) report on 'combating waterborne disease at
the household level' by (The International Network to Promote Household
Water Treatment and Safe Storage):
1.1 billion lack access to an 'improved' drinking water supply; many
more drink water that is grossly contaminated.
4 billion cases of diarrhoea occur annually, of which 88% is attributable
to unsafe water, and inadequate sanitation and hygiene.
1.8 million people die every year from diarrhoeal diseases, the vast
majority children under 5.
Lack of safe water perpetuates a cycle whereby poor populations
become further disadvantaged, and poverty becomes entrenched.
WHO estimates that 94% of diarrhoeal cases are preventable through
modifi cations to the environment, including through interventions to
increase the availability of clean water, and to improve sanitation and
hygiene.
The major drinking water contaminants are shown in Table 16.3 (Daniels
and Mesner, 2005). The most serious amongst them are microbiological
contamination. WHO guidelines make reference to the water supply situa-
tion common in many countries where water must be collected from a well
or standpipe, transported home and then stored for domestic use. In such
circumstances: 'Water that is transported or stored unhygienically may be
recontaminated, which represents a public health risk. Most recontamina-
tion is the result of behavioural patterns; if these can be changed, the health
risk can be reduced or eliminated' (WHO, 1997). In their
Water Handbook
,
UNICEF observe: 'There are many cases of water which is bacteria-free at
the source becoming contaminated during transportation, storage and con-
sumption. Any water supply project that neglects this aspect will be inef-
fective' (UNICEF, 1999).
There is now conclusive evidence that simple, acceptable, low-cost inter-
ventions at the household and community level are capable of dramatically
improving the microbial quality of household stored water and reducing
the attendant risks of diarrhoeal disease and death. Treating water at the
household level has been shown to be one of the most effective and cost-
effective means of preventing waterborne disease in development and
emergency settings. Promoting household water treatment and safe storage
(HWTS) helps vulnerable populations to take charge of their own water
security by providing them with the knowledge and tools to treat their
own drinking water (UNICEF, 2008). Household-level approaches to
drinking water treatment and safe storage are also commonly referred to
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