page 1
page 2
page 3 page 4
page 5
page 6
page 7
page 8
page 9
page 10
< prev - next > Disaster response mitigation and rebuilding Reconstruction Water Treatment during Reconstruction (Printable PDF)
Water Treatment During Reconstruction
Practical Action
Whilst a relief agency is likely to organise the water supply, there is also a need to ensure people
retain a level of independence, and in line with principles of People-Centred Reconstruction,
encourage their own construction and/or administration of water treatment methods. Boiling water
can ensure complete sterilisation, but requires significant energy inputs that are normally not
available in sufficient quantity. Instead, people require practical treatment methods that give the
best possible result considering the circumstances.
Some practical solutions are now detailed that can assist with water treatment. They are
considered applicable or adaptable to the emergency stage (and further) of the reconstruction
process. Key attributes include quick and simple construction and operation, portability and
Point-of-Use Chlorination
Chlorination is a simple but effective method of disinfecting water supplies, killing the majority
(but not all) of bacterial contaminations. It is relatively inexpensive and usually readily available
in several forms.
When added to water, chlorine destroys the membranes of micro-organisms and kills them. At
temperatures between 18˚C and 30˚C it requires approximately 30 minutes to achieve
disinfection, but this can be longer for lower temperature. Additionally, it is only effective in water
of low turbidity; silt and sediment can block this process from occurring and the treatment is
ineffective, and water supplies should undergo a basic filter treatment before chlorine is added.
The more thoroughly the water can be filtered before chlorination the better, although this can be
limited in an emergency context.
Chlorination should be undertaken by the dispensing agency, as it is important to add the correct
amount; too little can result in ineffective disinfection, whilst too much can leave residual
chlorine which is damaging to health. It is unlikely that a correct standard can be upheld, and it
would require each individual to have access to measuring equipment to determine water
contamination and chlorine levels. WEDC and WHO have compiled a technical note on water
chlorination, available here.
Clay Water Filters
A simple method for filtering and storing potable water
has been developed by the Sri Lanka Red Cross agency,
consisting of a porous clay pot placed into a plastic liner.
The plastic liner has a spigot at the bottom to allow
controlled access to the filtered water.
The clay filter element is treated with colloidal silver,
killing bacteria and removing sediments as water passes
through to the receptacle below. Water quality tests have
shown in kills approximately 98% of diarrhoea causing
bacteria, and can filter up to 40 litres of water per day.
The technology has been widely implemented in some
areas of Sri Lanka, having been developed in response to
the need for safe water supplies for displaced people in
the aftermath of the 2004 tsunami.
People who use the device are encouraged to clean and
maintain their own pot, helping to develop an
understanding of water hygiene in the process.
The Practical Action report ‘Clay Water Filters’ has a more
detailed description of the manufacture and operation of
the product. It is available here.
Figure 1: Diagram and picture of Clay
Water Filter. Source: Practical Action
Technical Brief Clay Water Filters