What is SODIS Method [Solar Water Disinfection]?

Well, what is SODIS Method? Before we learn the same, the SODIS is abbreviated as Solar Water Disinfection. Usually, the SODIS (Solar Water Disinfection) started as an initiative of Eawag, the Swiss Federal Institute of Aquatic Science and Technology. 

Eawag supports the improvement and dissemination of the SODIS method (Solar Water Disinfection) through research in microbiology, health, educational strategies, and PET bottles. An enthusiastic team in Switzerland provides technical and project management support for SODIS projects in 25 countries.

What is SODIS Method

In 2011, Eawag and the Swiss NGO Helvetas Swiss Intercooperation partnered with the aim of jointly promoting the SODIS method around the world. In the context of this partnership, Helvetas Swiss Intercooperation is carrying out the projects that support the promotion of household water treatment, including the SODIS method.

What is SODIS Method? Points to be Considered While Applying the SODIS Method

The SODIS method is very easy to apply: a transparent PET bottle is cleaned with soap. The bottle is then filled with water and placed in full sunlight for at least 6 hours. The water has been disinfected and can be drunk.

SODIS Method full form

What are the Points to be Considered?

The following are the points to be considered while applying the SODIS method (Solar Water Disinfection). Let’s go through them one by one now straightforwardly.

Bottle material, color, and shape

The use of PET bottles is recommended in the application of the SODIS method because they are light and do not break. They are also easy to obtain in many regions. However, glass bottles or special bags can also be used. PET bottles are generally labeled as such, but they do not receive the same name in all countries.

The bottles must be transparent and colorless

PET bottles often have a bluish tint. This is not a problem. Badly damaged bottles must be replaced. The bottles must not contain more than 3 liters.


If the water is very cloudy, the effectiveness of the method is reduced. It is very easy to determine if the water is clear enough: The filled PET bottle should be placed on top of a newspaper. Now you should look at the bottom of the bottle from the neck at the top and through the water.

SODIS stands for

If the letters of the newspaper headline are legible, that water can be used. If the letters are not legible, the water must be filtered. This test corresponds to turbidity of 30 NTU.


Cloud cover affects the intensity of solar radiation and therefore also the effectiveness of the method. If less than half the sky is cloudy, 6 hours will be enough to completely disinfect the water. If more than half of the sky is covered with clouds, the bottle should be placed in the sun for 2 consecutive days.


The method does not work satisfactorily during long periods of rain. On these days, we recommend collecting rainwater.

Preventing re-contamination

solar water disinfection science project

The treated water should be kept in the bottle and drunk directly from the bottle, or poured into a cup or glass immediately before drinking. In this way, it is possible to prevent the treated water from being contaminated again.

These are the points to be considered always while applying the SODIS method (Solar Water Disinfection) obtained for the purification of water. I guess the above details shared were helpful to you.


As we discussed, the full form of SODIS is Solar Water Disinfection. This method helps to purify the water removing various types of contaminants. Anyhow other than this, if you like to learn more interesting tutorials, keep in touch with the best water purifier reviews anytime and acquire the needful information now itself without making any delay.

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