SODIS: Solar Water Disinfection

3 litres of water per day.

According to the Water Encyclopedia, that’s how much the average human needs per day for survival.  This amount increases with physical activity and with temperature.  Aside from replacing our body’s water we need water for a number of purposes including agriculture, cooking sanitation and hygiene.  This amounts to 50 liters required to meet human needs.

Treatment and delivery of water costs a lot of money.  The water needs to be pumped from a source like a lake, river or well to a water treatment plant.  Depending on requirements the water can be treated in different ways.

Commonly it is filtered and then disinfected with a chemical such as chlorine.  However, the equipment to do this costs thousands of dollars.  Plants also need a building to be situated in, sensors to monitor the process, and an operator to run and maintain the system.

Costs for this are often in the hundreds of thousands of dollars range and as a result many impoverished communities can not afford these costs.  With over 5.4 billion people on Earth living on less than $10 a day, this is a serious problem.

The Swiss Federal Institute of Aquatic Science and Technology has developed an extremely cheap and easy way for people to disinfect their drinking water.  The method is called Solar Water Disinfection (SODIS) and it uses the sun’s radiant energy and recycled plastic bottles.

The following diagrams give you the gist of how SODIS works:

UV radiation from the sun, the nasty stuff that gives us sun burns, passes through the bottles and into the water.  This energy interferes with the metabolism of the microscopic organisms in water that cause illness rendering them harmless.  This is a very simple and effective method.

The catch though is that this method is not effective during rainfall.

Check out the following 10 minute video about SODIS being implemented in the Philippines:

So how can you help with an issue such as this?

1. Spread awareness whenever possible, knowledge is power.  You can become a fan of SODIS on Facebook .

2. Recycle!  Instead of throwing away plastic bottles, recycle them.  You may help to save a life.

To learn more about the Swiss Federal Institute of Aquatic Science and Technology’s SODIS water disinfection method, visit their web site.

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