Providing safe drinking water - Info for organisations in the field

This just in from Kris Shankar krissh@microsoft.com

Kris has been contacting various disaster relief organizations regarding providing drinking water to the tsunami survivors.

There is a simple, foolproof process called SODIS (Solar Water Disinfection) that can enable the survivors to make their own safe drinking water supply even from polluted water sources while waiting for relief supplies to arrive.

Given the logistical problems in ensuring steady drinking water supplies to many of the tsunami hit areas, the rapid dissemination of information about SODIS to survivors could save many lives.

SODIS was developed in 1991 by EAWAG (The Swiss Federal Institute for Environmental Science and Technology) and SANDEC (EAWAG's Department of Water and Sanitation in Developing Countries) and has been recommended by the WHO (World Health Organization) for use in 3rd world countries and other locations where clean water is scarce.

You can get a very useful description, both text and pictorial, of the SODIS process on http://www.sodis.ch/Text2002/T-Howdoesitwork.htm - the material on this web page can be used for non-profit uses with no worries about copyright issues (see www.sodis.ch for details). More details on the benefits and limitations of the SODIS process are also available on this web page.

At the bottom of this email, I have abstracted a brief description of the SODIS process for purifying water for your quick review.

Relief organizations should consider printing leaflets with the above pictorial description (accompanied by text in the local languages) and distribute these leaflets to all affected areas for use by survivors. This will give them a viable option for drinking water while waiting for sustained relief. Obviously, speed is of the essence in getting this information into the hands of survivors.

SODIS is being used widely in places where there is awareness of the technique. See the following links if you want to read descriptions of SODIS use in various countries:

SODIS use in Brazil
SODIS use in Uzbekistan
SODIS use in Kenya, Thailand
SODIS use in Kenya
SODIS use in Nepal

-------- SODIS Description I wrote up for your quick review --------

Unsafe drinking water causes diseases such as diarrhoea, cholera, typhoid and dysentery. One of the ways of avoiding this is by drinking clean safe water, which is boiled or treated by SODIS.

Solar Water Disinfection (SODIS) is a water treatment method, which uses the sun. This method requires a discarded 2 liter plastic bottle. After filling the bottle to about 3/4ths capacity with water, shake it vigorously to aerate the water, close it, and place it in direct sunlight for 6 – 8 hours . The heat and ultraviolet rays from the sun kill viruses, bacteria and microorganisms in the water. Where other methods of water treatment are not available, the use of SODIS can reduce sickness and can save life, particularly for infants, in families that have no access to good quality water.

How to use this method:

1. Use the cleanest water you can get. If your water is muddy, leave it in your bucket for sometime to settle down. Use a clean cup to fill your plastic bottle leaving the residue at the bottom.
2. Fill your plastic bottle to about 3/4ths capacity with water, shake it vigorously to aerate the water, close it.
3. Lay down the plastic bottle in the sun for example on the roof to keep it away from children.
4. Leave your plastic bottle in direct sunlight for at least 6 – 8 hours.
5. If it is cloudy, expose your plastic bottle in the sun for at least two days. Always remember to keep your plastic bottle clean. Take care so that the bottle is not too scratched. Replace your bottle if it gets too many scratches.

Advantages of this method compared to boiling:

* saves your time and less work is done compared to boiling water.
* saves your money because buying these bottles once is cheaper than buying charcoal or firewood every day to boil water. You can use old bottles as well.