The SODIS method of water disinfection is a simple, low-cost technology that uses solar energy to destroy illness-causing microorganisms. These contagious
microorganisms, which are transmitted through polluted water, are vulnerable to two aspects of solar light: UV-A radiation and the increase in water temperature that it causes. A synergy exists since the combined effect of these two aspects increases the mortality of the microorganisms by a factor that is much greater than that created by their individual effects.
To utilize the SODIS method, the contaminated water is placed in clear plastic bottles which are then exposed to solar light for six hours. If the temperature is more than 50° Centigrade, one hour of exposure will suffice. Either way, the exposure to the solar light kills the contagious germs, thus yielding disinfected water. Although it is necessary to expose the plastic bottles for two consecutive days when the sky is cloudy, the effectiveness of the treatment improves when the bottles are surrounded by reflective surfaces like sheets of metal, rooftops, or black plastic.
The SODIS method allows for the treatment of small quantities of water, typically in one- to two-liter bottles, and is ideal in its simplicity for obtaining safe drinking water as it guarantees a 99% disinfection for viruses and harmful bacteria.
