The Effectiveness of Solar Disinfection
Bacteria, viruses, and other pathogens in water and food can cause diarrhea, stomach ache, fever, and death. These pathogens are too small to be seen, but can be detected with appropriate testing. Many of these pathogens are present in human and animal feces and can pass into water.
Solar disinfection, which relies on the ultraviolet (UVA) component of daylight, will inactivate bacteria, viruses, and some cysts. It has been proven effective against cholera, typhoid, dysentery, crytosporidium, giardia, many forms of diarrheal disease, and polio.
How to Use Solar Disinfection
The following are basic points of solar disinfection. They must be elaborated and adapted to local conditions.
Advantages and Limitations of Solar Disinfection
Solar disinfection is a simple, low cost method for disinfecting small quantities of drinking water. By relying on the ultraviolet (UVA) in daylight to disinfect bacteria, viruses, and other pathogens in the water, it does not require any chemicals and does not change the color or taste of water.
Solar disinfection does not require the availability or purchase of chemicals or equipment and is thus immediately accessible to millions of people throughout the world. It is appropriate and highly effective for use in emergencies and disasters and on an on-going basis in daily life where clean water is not available.
By helping reduce the incidence of diarrheal diseases, the use of solar disinfection can reduce human suffering, the economic cost of disease, and the additional burden on women of caring for sick children. Since it reduces the need for fuel and firewood, it has beneficial environmental effects.
Although solar disinfection disinfects bacteria and viruses, its effect on some cysts and worms has not been fully researched and should not be assumed. It does not remove pesticides or chemical contaminants. It cannot be used with very turbid or cloudy water.
Drinking water purified by solar disinfection during one part of the day does not protect against consumption of contaminated drinking water at other times. While promoting health, clean water should not be considered to be a "medicine".
Use of solar disinfection should be combined with good hygiene such as washing hands after using the toilet, after cleaning a baby, after handling animals and before eating in order to reduce the incidence of disease.
For further information about GRI's Sun Water program, to offer suggestions, to discuss ways of partnering with us, and to engage in a dialogue regarding solar disinfection, please contact Peter Moulton, Ph.D., Executive Director at <email@example.com>
Global Resources Institute can be contacted at
last modified January 2006