Water Treatment During Reconstruction
Practical Action
Solar Water Disinfection
This is a very simple of method of removing or neutralising pathogens in water; by filling a plastic
bottle of contaminated water and exposing to direct sunlight for a few hours. The raised
temperature of the water and UV rays from sunlight combine to kill off a variety of protozoa,
bacteria, yeasts, viruses, algae and fungi
that can exist. The method has been shown
to remove up to 99.9% of pathogenic
bacteria from water supplies.
The effectiveness of the process is
dependent on the intensity of the sunlight
(i.e. process can be completed in 6 hours
with strong, direct sunlight, but up to 2 days
for intermittent sun), and the turbidity of the
water. It is recommended the process is
ineffective for water with a turbidity of over
30 NTU.
The Practical Action Technical Brief provides more
detailed information here.
Figure 2: Bottles are left for the day
Photo: Practical Action / Zul
The above two methods of water treatment are simple and effective processes that can be
operated by individual, displaced people in an emergency scenario. The key benefits are that they
can be used to ensure most contaminated water supplies from point sources are safe for
consumption, with a greatly reduced risk of spread of disease.
Transition
These methods can provide a consistent, safe supply during the early stages of reconstruction.
During a transitional stage, it is often unknown how long people will be displaced for, and whether
the location is permanent or not. The portability of these methods is essential in this respect.
Once emergency supplies have been secured, a key upgrade to distribution infrastructure is
improved storage facilities. These provide much greater opportunity for coagulation and
sedimentation, removing physical contaminants and improving the effectiveness of disinfection
treatments as well.
Large tanking facilities are outside the scope of this report, but detailed information can be found
through various links at the Practical Answers Emergency Relief homepage.
Other Small-Scale Water Treatments (External Sources)
As well as the above examples, there are several other small-scale filter technologies being
developed:
Aquabox
http://www.aquabox.org/newsitem.asp?id=135
Emergency relief water tank and filtration kits - It is filled with a selection of warm clothing,
useful hardware and hygiene items. It also contains a filter cartridge and a matching supply of
water-treatment tablets. Once the welfare contents have been removed, each Aquabox can be
used to purify up to 1100 litres of water. The Aquabox Gold is a sponsored box that is filled by
Aquabox with welfare items and two filter kits extend its water purification life. AQUA30 is for
situations where the need is more prolonged or arises regularly, but permanent solutions cannot
yet be provided. AQUA30 is supplied filled with 30 filter cartridges and the required water-
treatment tablets.
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