Solar water disinfection, also known as SODIS, is a simple and effective way to purify contaminated drinking water. All you need is a transparent plastic bottle and some sunlight.

To use SODIS, fill the bottle with contaminated water and expose it to full sunlight for at least six hours. The sun’s UV-A radiation (wavelength 320-400nm) and the increased water temperature work together to kill harmful bacteria and viruses in the water. If the water temperature reaches 50°C or higher, the disinfection process is three times faster.

Mason jars can also be used for solar water disinfection, though plastic bottles may be easier to find and lighter to carry in a survival situation.

It’s important to note that SODIS is just one method of water purification and it’s always a good idea to have multiple methods at your disposal in case of an emergency.