Can sunlight effectively disinfect contaminated water?
Written by
Gina Mason
Reviewed by
Prof. William Dalton, Ph.D.Sunlight can effectively disinfect water through appropriate methods, such as the SODIS method for water purification. These water purification methods use UV radiation, which destroys the harmful microorganisms. Transparent plastic bottles can be employed in a simple way for treatment. I have seen and noted this SODIS technology during field work in developing countries, and it has remarkably reduced water-borne disease when used properly.
Efficacy of SODIS implies particular proportions and forms. Make use of transparent PET bottles having a capacity not greater than 2 liters, having a good supply of a clear power of fastigiation. Placing these bottles with the lateral faces exposed on reflective surfaces capable of receiving the sun's rays, with a declination of 30°, it is necessary that the bottles are kept in the said position at least 6 hours in a high degree of *ultraviolet* light, or else they must be kept for 48 consecutive hours in cloudy weather.
Preparation Protocol
- Pre-filter cloudy water through clean cloth
- Remove visible debris and sediment
- Use bottles without scratches or discoloration
Exposure Management
- Position bottles on metal or dark surfaces
- Rotate bottles hourly for even exposure
- Check temperature increase as indicator
- Extend time during partial cloud cover
Safety Verification
- Observe reduced organic odor after treatment
- Combine with taste test when possible
- Use residual chlorine test strips if available
Be aware of the critical disadvantages of solar disinfecting. SODIS does not remove chemical contaminants (such as pesticides, heavy metals). It may take a long exposure for cysts, such as Cryptosporidium. Always use pre-filtration with SODIS for best results. These limits make SODIS only good for biological contamination.
Make supplementary provisions for safety in full. Incorporate cloth pre-filtration to get rid of any sediment. Use activated charcoal when possible for the reduction of chemical compounds. Store the treated water in disinfected vessels. In the case of an emergency, make use of SODIS in conjunction with boiling for protection against all varieties of pathogens.
Set up a systematic regime of SODIS treatment, repeating for best results. Train family members in the correct methods. Construct disinfection sites with reflective surfaces if possible. Check daily UV indexes for the best time to treat the water. These practices will guarantee effective water safety using the free sunlight resource.
Read the full article: 9 Effective Ways to Purify Water at Home
